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All the ideas for 'From an Ontological Point of View', 'fragments/reports' and 'On the Plurality of Worlds'

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158 ideas

1. Philosophy / B. History of Ideas / 2. Ancient Thought
Diogenes of Apollonia was the last natural scientist [Diogenes of Apollonia, by Simplicius]
     Full Idea: Diogenes of Apollonia was more or less the last of those who made a study of natural science.
     From: report of Diogenes (Apoll) (fragments/reports [c.440 BCE], A05) by Simplicius - On Aristotle's 'Physics' 9.25.1
     A reaction: He quotes Theophrastus
1. Philosophy / D. Nature of Philosophy / 5. Aims of Philosophy / a. Philosophy as worldly
Honesty requires philosophical theories we can commit to with our ordinary commonsense [Lewis]
     Full Idea: The maxim of honesty: never put forward a philosophical theory that you yourself cannot believe in your least philosophical and most commonsensical moments.
     From: David Lewis (On the Plurality of Worlds [1986], 2.8)
     A reaction: I take it as important that this test is according to the philosopher's commonsense, and not according to some populist idea. This would allow, for example, for commonsense to be sensitive to scientific knowledge, or awareness of the logic.
1. Philosophy / F. Analytic Philosophy / 1. Nature of Analysis
Analysis reduces primitives and makes understanding explicit (without adding new knowledge) [Lewis]
     Full Idea: The object of analysis is to reduce our burden of primitive notions, and to make tacit understanding explicit - not to bootstrap ourselves into understanding what we didn't understand at all beforehand.
     From: David Lewis (On the Plurality of Worlds [1986], 3.2)
     A reaction: I am particularly keen on the idea of 'making tacit understanding explicit'. I connect this with faith in intuition, and with the coherence view of justification.
1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
If you begin philosophy with language, you find yourself trapped in it [Heil]
     Full Idea: If you start with language and try to work your way outwards, you will never get outside language.
     From: John Heil (From an Ontological Point of View [2003], Pref)
     A reaction: This voices my pessimism about the linguistic approach to philosophy (and I don't just mean analysis of ordinary language), though I wonder if the career of (say) John Searle is a counterexample.
2. Reason / B. Laws of Thought / 6. Ockham's Razor
Parsimony does not imply the world is simple, but that our theories should try to be [Heil]
     Full Idea: A commitment to parsimony is not a commitment to a conception of the world as simple. The idea, rather, is that we should not complicate our theories about the world unnecessarily.
     From: John Heil (From an Ontological Point of View [2003], 13.6)
     A reaction: In other words, Ockham's Razor is about us, not about the world. It would be absurd to make the a priori assumption that the world has to be simple. Are we, though, creating bad theories by insisting that they should be simple?
A theory with few fundamental principles might still posit a lot of entities [Heil]
     Full Idea: It could well turn out that a simpler theory - a theory with fewer fundamental principles - posits more entities than a more complex competitor.
     From: John Heil (From an Ontological Point of View [2003], 13.6)
     A reaction: See also Idea 4036. The point here is that you can't simply translate Ockham as 'keep it simple', as there are different types of simplicity. The best theory will negotiate a balance between entities and principles.
3. Truth / A. Truth Problems / 6. Verisimilitude
Verisimilitude might be explained as being close to the possible world where the truth is exact [Lewis]
     Full Idea: We might explain the closeness to the truth (or 'verisimilitude') in terms of closeness of possible worlds. A theory is close to the truth to the extent that our world resembles some world where that theory is exactly true.
     From: David Lewis (On the Plurality of Worlds [1986], 1.3)
     A reaction: [Lewis cites Risto Hilpinen for this thought] I am always puzzled why Lewis and co. talk of whole worlds in their accounts. If I am close to the truth about cooking a good omelette, what has the rest of the world got to do with it?
3. Truth / B. Truthmakers / 4. Truthmaker Necessitarianism
The view that truth making is entailment is misguided and misleading [Heil]
     Full Idea: I argue that the widely held view that truth making is to be understood as entailment is misguided in principle and potentially misleading.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: If reality was just one particle, what would entail the truths about it? Suppose something appears to be self-evident true about reality, but no one can think of any entailments to derive it? Do we assume a priori that they are possible?
4. Formal Logic / F. Set Theory ST / 8. Critique of Set Theory
God does not create the world, and then add the classes [Heil]
     Full Idea: It is hard to see classes as an 'addition of being'; God does not create the world, and then add the classes.
     From: John Heil (From an Ontological Point of View [2003], 13.4 n6)
     A reaction: This seems right. We may be tempted into believing in the reality of classes when considering maths, but it seems utterly implausible when considering trees or cows.
5. Theory of Logic / G. Quantification / 6. Plural Quantification
Quantification sometimes commits to 'sets', but sometimes just to pluralities (or 'classes') [Lewis]
     Full Idea: I consider some apparent quantification over sets or classes of whatnots to carry genuine ontological commitment to 'sets' of them, but sometimes it is innocent plural quantification committed only to whatnots, for which I use 'class'.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5 n37)
     A reaction: How do you tell whether you are committed to a set or not? Can I claim an innocent plurality each time, while you accuse me of a guilty set? Can I firmly commit to a set, to be told that I can never manage more than a plurality?
7. Existence / A. Nature of Existence / 2. Types of Existence
There are only two kinds: sets, and possibilia (actual and possible particulars) [Lewis, by Oliver]
     Full Idea: Lewis's multi-purpose ontology seems to have only two kinds: sets and possibilia (actual and possible particulars).
     From: report of David Lewis (On the Plurality of Worlds [1986]) by Alex Oliver - The Metaphysics of Properties 3
     A reaction: This is awfully like the ontology of his teacher Quine, but with the wicked addition of modal properties. It is no wonder that Lewis was a bit vague about the concrete boundary, as both of his kinds seem to be abstract. His Achilles' Heel?
7. Existence / C. Structure of Existence / 2. Reduction
The reductionist programme dispenses with levels of reality [Heil]
     Full Idea: The reductionist programme dispenses with levels of reality.
     From: John Heil (From an Ontological Point of View [2003], 04.3)
     A reaction: Fodor, for example, claims that certain causal laws only operate at high levels of reality. I agree with Heil's idea - the notion that there are different realities around here that don't connect properly to one another is philosopher's madness.
7. Existence / C. Structure of Existence / 3. Levels of Reality
There are levels of organisation, complexity, description and explanation, but not of reality [Heil]
     Full Idea: We should accept levels of organisation, levels of complexity, levels of description, and levels of explanation, but not the levels of reality favoured by many anti-reductionists. The world is then ontologically, but not analytically, reductive.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: This sounds right to me. The crunch questions seem to be whether the boundaries at higher levels of organisation exist lower down, and whether the causal laws of the higher levels can be translated without remainder into lower level laws.
7. Existence / C. Structure of Existence / 5. Supervenience / a. Nature of supervenience
Supervenience concerns whether things could differ, so it is a modal notion [Lewis]
     Full Idea: The idea of supervenience is when there could be no difference of one sort without difference of another sort. ..Clearly this 'could' indicates modality, and without modality we have nothing of interest.
     From: David Lewis (On the Plurality of Worlds [1986], 1.2)
     A reaction: This might explain why philosophers are going to be more at home with the concept than neuroscientists would be.
7. Existence / D. Theories of Reality / 2. Realism
Realism says some of our concepts 'cut nature at the joints' [Heil]
     Full Idea: Realism is sometimes said to involve a commitment to the idea that certain of our concepts, those with respect to which we are realists, 'carve reality at the joints'.
     From: John Heil (From an Ontological Point of View [2003], 14.11)
     A reaction: Clearly not all concepts cut nature at the joints (e.g. we have concepts of things we know to be imaginary). Personally I am committed to this view of realism. I try very hard to use concepts that cut accurately; why shouldn't I sometimes succeed?
7. Existence / D. Theories of Reality / 4. Anti-realism
Anti-realists who reduce reality to language must explain the existence of language [Heil]
     Full Idea: Anti-realist philosophers, and those who hope to reduce metaphysics to (or replace it with) the philosophy of language, owe the rest of us an account of the ontology of language.
     From: John Heil (From an Ontological Point of View [2003], 20.6)
     A reaction: A nice turning-the-tables question. In all accounts of relativism, x is usually said to be relative to y. You haven't got proper relativism if you haven't relativised both x and y. But relativised them to what? Nietzsche's 'perspectivism' (Idea 4420)?
7. Existence / D. Theories of Reality / 7. Fictionalism
Abstractions may well be verbal fictions, in which we ignore some features of an object [Lewis]
     Full Idea: The inevitable hypothesis is that abstractions are verbal fictions. We say we are speaking about abstractions when we are speaking abstractly about the original thing. We are ignoring some features, not introducing a new thing lacking those features.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: Thus Lewis ends up pretty close to Locke and the traditional view. This makes abstraction not a feat of platonic perception, in which magical non-material objects are spotted, but a feat of counterfactual imagination.
7. Existence / D. Theories of Reality / 10. Vagueness / d. Vagueness as linguistic
Vagueness is semantic indecision: we haven't settled quite what our words are meant to express [Lewis]
     Full Idea: I regard vagueness as semantic indecision: where we speak vaguely, we have not troubled to settle which of some range of precise meanings our words are meant to express.
     From: David Lewis (On the Plurality of Worlds [1986], 4.4 n32)
     A reaction: But that seems to leave the problem of how you are going to decide the boundaries of 'heap' or 'bald', if we all agree to become more precise. In law precise boundaries are often drawn a bit arbitrarily, simply because a boundary is needed.
Whether or not France is hexagonal depends on your standards of precision [Lewis]
     Full Idea: Say that France is hexagonal, and you thereby set the standards of precision low, and you speak the truth; say that France is not hexagonal (preferably on some other occasion) and you set the standards high, and again you speak the truth.
     From: David Lewis (On the Plurality of Worlds [1986], 4.5)
     A reaction: This is very persuasive. It fits with my views on justification, which are to do with how high I (or more often 'we') decide to set the standards, thereby defining knowledge for that occasion. Hm. Has Lewis cracked vagueness? [P.S. NO!]
7. Existence / E. Categories / 5. Category Anti-Realism
Concepts don't carve up the world, which has endless overlooked or ignored divisions [Heil]
     Full Idea: Concepts do not 'carve up' the world; the world already contains endless divisions, most of which we remain oblivious to or ignore.
     From: John Heil (From an Ontological Point of View [2003], 05.3)
     A reaction: Concepts could still carve up the world, without ever aspiring to do a complete job. We carve up the aspects that interest us, but the majority of the carving is in response to natural divisions, not whimsical conventions.
8. Modes of Existence / B. Properties / 1. Nature of Properties
Surely 'slept in by Washington' is a property of some bed? [Lewis]
     Full Idea: That the most noteworthy property of this bed is that George Washington slept in it - surely this is true on some legitimate conception of properties?
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: Wrong! This example is a nice clear test case. This is an absurd slippery slope. A bed he once looked at? I would have thought this was a relation the bed once entered into, and a relation isn't a property.
Properties don't have degree; they are determinate, and things have varying relations to them [Lewis]
     Full Idea: I have made no place for properties that admit of degree, so that things may have more or less of the same property. There are plain properties, and then there are relations to them.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: An interesting question, little discussed. Elsewhere, Lewis ascribes all vagueness to our inadequate predicates, rather than to the world, which I find quite persuasive.
The 'abundant' properties are just any bizarre property you fancy [Lewis]
     Full Idea: Properties are 'sparse' or 'abundant'. The abundant properties may be as extrinsic, as gruesomely gerrymandered, as miscellaneously disjunctive, as you please. They pay no heed to the qualitative joints, but carve things up every which way.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: This seems to be a logician's idea, which is needed for the notion of a set as pure extension, but it has very little to do with what I understand by the word 'property'. Better to call it a 'categorization'. E.g. filing George W. Bush under 'jackal'.
8. Modes of Existence / B. Properties / 2. Need for Properties
To be a 'property' is to suit a theoretical role [Lewis]
     Full Idea: To deserve the name of 'property' is to be suited to play the right theoretical role. It is wrong to speak of 'the' role associated with the word 'property', as if it were fully and uncontroversially settled.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: Once again I see a chicken-and-egg problem. Surely something has a theoretical role because of its intrinsic character, or its prior definition? How could you formulate a theory if you lacked properties? We don’t meet properties as gaps in theories.
8. Modes of Existence / B. Properties / 4. Intrinsic Properties
All of the natural properties are included among the intrinsic properties [Lewis]
     Full Idea: It cannot be said that all intrinsic properties are perfectly natural, ...but it can plausibly be said that all perfectly natural properties are intrinsic.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: Idea 15742 give the example he uses to support this claim. I like the concept of 'intrinsic' properties, but cannot currently see any use for the concept of 'natural' ones.
A disjunctive property can be unnatural, but intrinsic if its disjuncts are intrinsic [Lewis]
     Full Idea: A property can be unnatural by reason of disjunctiveness, as the property of being tripartite-or-liquid-or-cubical is, and it is intrinsic if its disjuncts are.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: This strikes me as being utterly, shockingly and disgracefully wrong. A disjunction can't possibly be a property. Can a person have the property of being 'fat or thin'? A disjunction offers candidates for properties, not the properties themselves.
If a global intrinsic never varies between possible duplicates, all necessary properties are intrinsic [Cameron on Lewis]
     Full Idea: Lewis defines a globally intrinsic property as one that never varies between duplicates across possible worlds. This has the immediate problem that any property that is necessarily had, or necessarily lacked, by every thing will be intrinsic.
     From: comment on David Lewis (On the Plurality of Worlds [1986], p.61-2) by Ross P. Cameron - Intrinsic and Extrinsic Properties 'Analysis'
     A reaction: [He also cites Langton and Lewis 1998] To me this is the sort of tangle you get into when you equate properties with predicates. The problem seems to concern necessary predicates (but those may not be necessary properties).
Global intrinsic may make necessarily coextensive properties both intrinsic or both extrinsic [Cameron on Lewis]
     Full Idea: If a globally intrinsic properties are those that never vary between duplicates across possible worlds, then necessarily coextensive properties will either be both intrinsic or both extrinsic.
     From: comment on David Lewis (On the Plurality of Worlds [1986], p.61-2) by Ross P. Cameron - Intrinsic and Extrinsic Properties 'Analysis'
     A reaction: Presumably this problem would arise if some intrinsic property entailed an extrinsic property (or, less likely, vice versa). These sorts of problems arise when you try to define everything extensionally (even across possible worlds).
8. Modes of Existence / B. Properties / 5. Natural Properties
We might try defining the natural properties by a short list of them [Lewis]
     Full Idea: We might try defining the natural properties by a short list, of the mass properties, charge properties, quark properties and flavours...
     From: David Lewis (On the Plurality of Worlds [1986], 1.5 n47)
     A reaction: He rejects this because of possible natural properties in other possible worlds. Defining anything by a list seems like cheating. Does John, Paul, George and Ringo 'define' something?
Natural properties give similarity, joint carving, intrinsicness, specificity, homogeneity... [Lewis]
     Full Idea: Sharing of [perfectly natural properties] makes for qualitative similarity, they carve at the joints, they are intrinsic, they are highly specific, the sets of their instances are ipso facto not highly miscellaneous.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: All this sounds like just what I want, but when I read Lewis he seems to be arriving at these natural properties by the wrong route. Too much Hume, too much extensionalism.
We can't define natural properties by resemblance, if they are used to explain resemblance [Lewis]
     Full Idea: Shall we say that natural properties are the ones whose instances are united by resemblance? - Not if we are going to say that resemblance is the sharing of natural properties.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: The target of this appears to be the proposal of Quinton. By now I have totally given up on so-called 'natural' properties. Lewis says the circularity (also in Idea 15743) is a reason to treat 'natural' here as primitive (though he rejects that).
Defining natural properties by means of laws of nature is potentially circular [Lewis]
     Full Idea: Shall we say that natural properties are the ones that figure in laws of nature? - Not if we are going to use naturalness of properties when we draw the line between laws of nature and accidental regularities.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: Personally I wouldn't dream of defining anything by saying that it figured in laws of nature. The laws, if there be such (see Mumford) are built up from more fundamental components, such as (perhaps) properties.
I don't take 'natural' properties to be fixed by the nature of one possible world [Lewis]
     Full Idea: Some people suppose my natural properties are distinguished by nature, and hence natural in one world and not another. I intend properties to be natural or unnatural simpliciter, not relative to one or another world.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5 n44)
     A reaction: This is an important warning for the likes of me. I've have begun to doubt the utility of the term 'natural' property, and this reinforces my view.
Sparse properties rest either on universals, or on tropes, or on primitive naturalness [Lewis, by Maudlin]
     Full Idea: Lewis surveys three accounts of sparse properties: a set of objects instantiating a single universal; a set of objects having as parts duplicates of some trope; and a set distinguished by a further unanalyzable, primitive characteristic of naturalness.
     From: report of David Lewis (On the Plurality of Worlds [1986], p.60-) by Tim Maudlin - The Metaphysics within Physics
     A reaction: The very idea of suggesting that a property is some set of objects strikes me as bizarre. I present you with a table full of objects and say that is the complete set of some property. You then have to study the objects to find out what the property is.
8. Modes of Existence / B. Properties / 9. Qualities
I think of properties as simultaneously dispositional and qualitative [Heil]
     Full Idea: Some philosophers who accept that properties are intrinsic features of objects regard them as pure powers, pure dispositionalities; I prefer to think of properties as simultaneously dispositional and qualitative.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: I am uneasy about 'qualitative' as a category, and am inclined to reduce it to being a dispositional power to cause primary and secondary qualities in observers. Roughness is only a power, not a quality, if there are no observers.
8. Modes of Existence / B. Properties / 10. Properties as Predicates
There is the property of belonging to a set, so abundant properties are as numerous as the sets [Lewis]
     Full Idea: The abundant properties far outrun the predicates of any language we could possibly possess. ...Properties are as abundant as the sets, because for any set whatever, there is the property of belonging to that set.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: The idea of calling such things 'properties' strikes me as preposterous, but it is interesting that we confront truths which outrun our predicates. We can't have all of these predicates together, but there is no impediment to any one of them.
A predicate applies truly if it picks out a real property of objects [Heil]
     Full Idea: When a predicate applies truly to an object, it does so in virtue of designating a property possessed by that object and by every object to which the predicate truly applies (or would apply).
     From: John Heil (From an Ontological Point of View [2003], 03.3)
     A reaction: I am sympathetic to Heil's aim of shifting our attention from arbitrary predicates to natural properties, but it won't avoid Fodor's problem (Idea 7014) that all kinds of whimsical predicates will apply 'truly', but fail to pick out anything significant.
8. Modes of Existence / B. Properties / 11. Properties as Sets
A property is the set of its actual and possible instances [Lewis, by Oliver]
     Full Idea: Lewis proposes that a property is the set of its actual and possible instances.
     From: report of David Lewis (On the Plurality of Worlds [1986], 1.5) by Alex Oliver - The Metaphysics of Properties 10
     A reaction: I just can't make sense of any proposal that a property is a set. Things fall into natural sets because they have properties. Only a philosopher would believe such a weird proposal as this one. Triangular and trilateral?
The property of being F is identical with the set of objects, in all possible worlds, which are F [Lewis, by Cameron]
     Full Idea: Lewis thought that the property of being F was identical with the set of objects, in all possible worlds, which are F.
     From: report of David Lewis (On the Plurality of Worlds [1986], §1.5) by Ross P. Cameron - Intrinsic and Extrinsic Properties
     A reaction: I can't make head or tail of a theory which says that a property is a set of objects. I'll show you a room full of objects and tell you they are a property. How are you going to work out what the property is? 'Being F' is a predicate, not a property!
Properties don't seem to be sets, because different properties can have the same set [Lewis]
     Full Idea: The usual objection to taking properties as sets is that different properties may happen to be coextensive. Creatures with hearts are creatures with kidneys. Talking donkeys are flying pigs (since there are none). Yet the properties differ.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: This is the difficulty which Lewis proposes to solve by defining properties across possible situations as well as actual ones, so that the properties can come apart. Nice move.
Accidentally coextensive properties come apart when we include their possible instances [Lewis]
     Full Idea: In modal realism, 'accidentally coextensive' properties are not coextensive. They only appear so when we ignore their other-worldly instances. If we consider all instances, then it never can happen that two properties are coextensive but might have been.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: It is not clear why this 'can never happen'. Maybe even God can't make a hearted creature without kidneys. Lewis is aware of this question.
If a property is relative, such as being a father or son, then set membership seems relative too [Lewis]
     Full Idea: A property that is instantiated in a relative way (such as being a father or a son) could not be the set of its instances? Is the thing to be included in the set or not?
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: He says philosophers contrive ways to define properties as functions, but he prefers to call such properties 'relations', and define them that way. It never even occurred to me that 'being a son' was one of my properties, but what do I know?
Trilateral and triangular seem to be coextensive sets in all possible worlds [Lewis]
     Full Idea: We can't take a property as sets of this-worldly instances, because two properties may be coextensive. Some say it is just as bad in all possible worlds, if the property is necessary, as when all triangles are trilateral, which seem different.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: [compressed] Renate/cordate is the standard example of the first problem. Lewis seems to equivocate over exactly what is meant by a property. I take the example to be a powerful objection to treating properties as sets.
I believe in properties, which are sets of possible individuals [Lewis]
     Full Idea: I believe in properties. That is, I have my candidates for entities to play the role and deserve the name. My principal candidates are sets of possible individuals.
     From: David Lewis (On the Plurality of Worlds [1986], 3.4)
     A reaction: I am bewildered by any claim that a property is a 'set'. The property of being a teaspoon is just a large pile of teaspoons (one pile in each possible world)? This is the tyranny of first-order logic in philosophy. Are sets more real than properties?
It would be easiest to take a property as the set of its instances [Lewis]
     Full Idea: The simplest plan for properties is to take a property just as the set of all its instances.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: I find this a weird and counterintuitive proposal. I suppose if you think maths has been reduced to set theory, you might want to reduce everything else, and then we can all go home. I thought things were in sets because of their properties.
8. Modes of Existence / B. Properties / 13. Tropes / a. Nature of tropes
You must accept primitive similarity to like tropes, but tropes give a good account of it [Lewis]
     Full Idea: If you will not countenance primitive similarity in any form, then trope theory is not for you. But if you will, then duplication of tropes is an especially satisfactory form of primitive similarity to take.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: This presents the question about tropes in a beautifully simple form. Perfect similarities seem fine, but partial similarities (red and pink things) are hard, and abstract reference (pinkness and redness) is even harder.
A theory of universals says similarity is identity of parts; for modes, similarity is primitive [Heil]
     Full Idea: The friend of universals has an account of similarity relations as relations of identity and partial identity; the friend of modes must regard similarity relations as primitive and irreducible.
     From: John Heil (From an Ontological Point of View [2003], 14.5)
     A reaction: We always seem to be able to ask 'in what respect' a similarity occurs. If similarity is 'primitive and irreducible', we should not be able to analyse and explain a similarity, yet we seem able to. I conclude that Heil is wrong.
8. Modes of Existence / B. Properties / 13. Tropes / b. Critique of tropes
Tropes need a similarity primitive, so they cannot be used to explain similarity [Lewis]
     Full Idea: Trope theory cannot analyse similarity, because duplication of tropes is itself a primitive relation of similarity.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: A reasonable reply to this one, I think, is that no one can explain or analyse similarity. To say that the same universal (or bunch of graded universals) is instantiated explains nothing. Maybe type-identity must be primitive in any theory?
Trope theory (unlike universals) needs a primitive notion of being duplicates [Lewis]
     Full Idea: Trope theory has the drawback that we need the primitive notion of duplicate tropes, whereas with universals we just say that it is one and the same universal through some charged particles.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: The normal term for this primitive is 'perfect resemblance', though that seems to make close resemblance a bit complicated and puzzling. I'm not sure if I understand resemblance as a feature of the world, rather than of our minds.
Trope theory needs a primitive notion for what unites some tropes [Lewis]
     Full Idea: Trope theory needs a primitive notion - 'instantion' in yet another sense - to say how the tropes that comprise a particle are united.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: Any theory which says that objects are just 'bundles' of tropes is asking for trouble. But if you say (with Lowe and others) that tropes are 'modes' of existing entities, you still have to give an account of the entity.
8. Modes of Existence / C. Powers and Dispositions / 3. Powers as Derived
Powers or dispositions are usually seen as caused by lower-level qualities [Heil]
     Full Idea: The modern default position on dispositionality is that powers or dispositions are higher-level properties objects possess by virtue of those objects' possession of lower-level qualitative (categorical) properties.
     From: John Heil (From an Ontological Point of View [2003], 09.2)
     A reaction: The new idea which is being floated by Heil, and which I prefer, is that dispositions or powers are basic. A 'quality' is a much more dubious entity than a power.
8. Modes of Existence / C. Powers and Dispositions / 6. Dispositions / a. Dispositions
Are a property's dispositions built in, or contingently added? [Heil]
     Full Idea: There is a dispute over whether a property's dispositionality is built into the property or whether it is a contingent add-on.
     From: John Heil (From an Ontological Point of View [2003], 09.4)
     A reaction: Put that way, the idea that it is built in seems much more plausible. If it is an add-on, an explanation of why that disposition is added to that particular property seems required. If it is built in, it seems legitimate to accept it as a brute fact.
8. Modes of Existence / D. Universals / 1. Universals
Universals recur, are multiply located, wholly present, make things overlap, and are held in common [Lewis]
     Full Idea: One and the same universal recurs; it is multiply located; it is wholly present in both instances, a shared common part whereby the two instances overlap. Being alike by sharing a universal is 'having something in common' in an absolutely literal sense.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: A helpful spelling out of the commitment involved (in Armstrong and others) in belief in universals. To me this is a convenient list of reasons why the whole proposal is nonsense. Why does Lewis take them seriously?
If particles were just made of universals, similar particles would be the same particle [Lewis]
     Full Idea: We cannot say that a particle is composed entirely of its several universals, because then another particle exactly like it would have the very same universals, and yet the two particles would not be the same.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: This is an argument either (implausibly) for haecceities or characterless substrata, or else for tropes (which are all separate, unlike universals). Particles as bundles of universals is not a theory I take seriously.
8. Modes of Existence / D. Universals / 2. Need for Universals
Universals explain one-over-many relations, and similar qualities, and similar behaviour [Heil]
     Full Idea: Universals can explain the one-over-many problem, and easily explain similarity relations between objects, and explain the similar behaviour of similar objects.
     From: John Heil (From an Ontological Point of View [2003], 13.1)
     A reaction: A useful summary. If you accept it, you seem to be faced with a choice between Plato (who has universals existing independently of particulars) and Armstrong (who makes them real, but existing only in particulars).
8. Modes of Existence / D. Universals / 3. Instantiated Universals
Universals aren't parts of things, because that relationship is transitive, and universals need not be [Lewis]
     Full Idea: It cannot be said that a universal is instantiated by anything that has it as a part, since the relation of part to whole is transitive. If charge is part of a particle, which is part of an atom, then charge is part of the atom, but an atom isn't charged.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: Given the total mystery involved in 'instantiation', it wouldn't surprise me if someone appealed to the part-whole relation, but all moves to explain instantiation are desperate. Make it a primitive, if you must, then tiptoe away.
8. Modes of Existence / D. Universals / 6. Platonic Forms / d. Forms critiques
How could you tell if the universals were missing from a world of instances? [Heil]
     Full Idea: Imagine a pair of worlds, one in which there are the universals and their instances and one in which there are just the instances (a world of modes). How would the absence of universals make itself felt?
     From: John Heil (From an Ontological Point of View [2003], 13.7)
     A reaction: A nice question for Plato, very much in the spirit of Aristotle's string of questions. Compare 'suppose the physics remained, but someone removed the laws'. Either chaos ensues, or you realise they were redundant. Same with Forms.
8. Modes of Existence / E. Nominalism / 2. Resemblance Nominalism
Similarity among modes will explain everthing universals were for [Heil]
     Full Idea: My contention is that similarity among modes can do the job universals are conventionally postulated to do.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: See Idea 4441 for Russell's nice objection to this view. The very process by which we observes similarities (as assess their degrees) needs to be explained by any adequate theory of properties or universals.
Similar objects have similar properties; properties are directly similar [Heil]
     Full Idea: Objects are similar by virtue of possessing similar properties; properties, in contrast, are not similar in virtue of anything.
     From: John Heil (From an Ontological Point of View [2003], 14.2)
     A reaction: I am not sure if I can understand the concept of similarity if there is no answer to the question 'In what respect?' I suppose David Hume is happy to take resemblance as given and basic, but it could be defined as 'sharing identical properties'.
8. Modes of Existence / E. Nominalism / 5. Class Nominalism
Objects join sets because of properties; the property is not bestowed by set membership [Heil]
     Full Idea: The set of red objects is the set of objects possessing a property: being red. Objects are members of the set in virtue of possessing this property; they do not possess the property in virtue of belonging to the set.
     From: John Heil (From an Ontological Point of View [2003], 12.2)
     A reaction: This seems to be a very effective denial of the claim that universals are sets. However, if 'being a Londoner' counts as a property, you can only have it by joining the London set. Being tall is more fundamental than being a Londoner.
9. Objects / A. Existence of Objects / 1. Physical Objects
Trope theorists usually see objects as 'bundles' of tropes [Heil]
     Full Idea: Philosophers identifying themselves as trope theorists have, by and large, accepted some form of the 'bundle theory' of objects: an object is a bundle of compresent tropes.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: This view eliminates anything called 'matter' or 'substance' or a 'bare particular'. I think I agree with Heil that this doesn't give a coherent picture, as properties seem to be 'of' something, and bundles always raise the question of what unites them.
Objects are substances, which are objects considered as the bearer of properties [Heil]
     Full Idea: I think of objects as substances, and a substance is an object considered as a bearer of properties.
     From: John Heil (From an Ontological Point of View [2003], 04.2)
     A reaction: This is an area of philosophy I always find disconcerting, where an account of how we should see objects seems to have no connection at all to what physicists report about objects. 'Considered as' seems to make substances entirely conventional.
9. Objects / B. Unity of Objects / 2. Substance / c. Types of substance
Maybe there is only one substance, space-time or a quantum field [Heil]
     Full Idea: It would seem distinctly possible that there is but a single substance: space-time or some all-encompassing quantum field.
     From: John Heil (From an Ontological Point of View [2003], 05.2)
     A reaction: This would at least meet my concern that philosophers' 'substances' don't seem to connect to what physicists talk about. I wonder if anyone knows what a 'quantum field' is? The clash between relativity and quantum theory is being alluded to.
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
Rather than 'substance' I use 'objects', which have properties [Heil]
     Full Idea: I prefer the more colloquial 'object' to the traditional term 'substance'. An object can be regarded as a possessor of properties: as something that is red, spherical and pungent, for instance.
     From: John Heil (From an Ontological Point of View [2003], 15.3)
     A reaction: A nice move, but it seems to beg the question of 'what is it that has the properties?' Objects and substances do two different jobs in our ontology. Heil is just refusing to discuss what it is that has properties.
9. Objects / B. Unity of Objects / 3. Unity Problems / c. Statue and clay
Statues and bronze lumps have discernible differences, so can't be identical [Heil]
     Full Idea: Applications of the principle of the indiscernibility of identicals apparently obliges us to distinguish the statue and the lump of bronze making it up.
     From: John Heil (From an Ontological Point of View [2003], 16.3)
     A reaction: In other words, statues and lumps of bronze have different properties. It is a moot point, though, whether there are any discernible differences between that statue at time t and its constituting lump of bronze at time t.
Do we reduce statues to bronze, or eliminate statues, or allow statues and bronze? [Heil]
     Full Idea: Must we choose between reductionism (the statue is the lump of bronze), eliminativism (there are no statues, only statue-shaped lumps of bronze), and a commitment to coincident objects?
     From: John Heil (From an Ontological Point of View [2003], 16.5)
     A reaction: (Heil goes on to offer his own view). Coincident objects sounds the least plausible view. Modern statues are only statues if we see them that way, but a tree is definitely a tree. Trenton Merricks is good on eliminativism.
9. Objects / C. Structure of Objects / 8. Parts of Objects / c. Wholes from parts
Mereological composition is unrestricted: any class of things has a mereological sum [Lewis]
     Full Idea: I claim that mereological composition is unrestricted: any old class of things has a mereological sum. Whenever there are some things, even out of different possible worlds, there is something composed of just those things.
     From: David Lewis (On the Plurality of Worlds [1986], 4.3)
     A reaction: To say the least, a rather unusual usage for the English word 'thing'. I presume that Lewis is in the grip of a slippery slope problem - that there is no way to define the borderline between things and non-things. Presumably 'class' is unrestricted too.
There are no restrictions on composition, because they would be vague, and composition can't be vague [Lewis, by Sider]
     Full Idea: Lewis says that if not every class has a fusion then there must be a restriction on composition. The only plausible restrictions would be vague ones, which is impossible, because then whether composition occurs would be vague. So every class has a fusion.
     From: report of David Lewis (On the Plurality of Worlds [1986], p.212-3) by Theodore Sider - Four Dimensionalism 9.1
     A reaction: This is Lewis's key argument in favour of unrestricted composition, his Vagueness Argument. Why can't composition be vague? If you gradually reassemble a broken mirror, at what point does the mirror acquire its unity?
9. Objects / D. Essence of Objects / 7. Essence and Necessity / a. Essence as necessary properties
An essential property is one possessed by all counterparts [Lewis, by Elder]
     Full Idea: For Lewis, if a property possessed by a given individual or kind is missing in some of the contextually relevant counterparts, that property is accidental to the individual or kind; if it is possessed by all of them, that property is essential.
     From: report of David Lewis (On the Plurality of Worlds [1986], 248-263) by Crawford L. Elder - Real Natures and Familiar Objects 1.4
     A reaction: This is a sophisticated version of the idea that essential properties are just necessary properties. It might make sense with a very sparse view of properties (mainly causal ones), but I think of essences as quite different from necessities.
9. Objects / E. Objects over Time / 1. Objects over Time
A thing 'perdures' if it has separate temporal parts, and 'endures' if it is wholly present at different times [Lewis]
     Full Idea: Something 'perdures' iff it persists by having different temporal parts, or stages, at different times, though no one part of it is wholly present at more than one time; whereas it 'endures' iff it persists by being wholly present at more than one time.
     From: David Lewis (On the Plurality of Worlds [1986], 4.2)
     A reaction: Only a philosopher would come up with a concept like perdurance. I'm thinking about this one, and will get back to you in a later-numbered idea... He compares perdurance to the way a road persists through space.
9. Objects / E. Objects over Time / 2. Objects that Change
Properties cannot be relations to times, if there are temporary properties which are intrinsic [Lewis, by Sider]
     Full Idea: The problem of 'temporary intrinsics' is that in one model we think of properties as relations to times (I am 'bent' relative to now), but change sometime involves intrinsic properties. I am just plain bent, not bent with respect to something else.
     From: report of David Lewis (On the Plurality of Worlds [1986], p.202-4) by Theodore Sider - Four Dimensionalism
     A reaction: [I've compressed Sider's summary] The question of whether intrinsic properties endure over time runs in parallel with the question of whether objects endure over time, and the two issues cannot be separated.
9. Objects / E. Objects over Time / 3. Three-Dimensionalism
Endurance is the wrong account, because things change intrinsic properties like shape [Lewis]
     Full Idea: The principal and decisive objection to endurance, as an account of the persistence of ordinary things, is the problem of temporary intrinsics. Persisting things change their intrinsic properties, such as their shape. My own shape keeps changing.
     From: David Lewis (On the Plurality of Worlds [1986], 4.2)
     A reaction: Presumably if something was going to endure through time it would need a shape. If it has no particular shape, it lacks identity? Lewis discusses the problem at length. Why is a precise shape essential to anything?
There are three responses to the problem that intrinsic shapes do not endure [Lewis]
     Full Idea: The problem for the endurance view of temporary intrinsic properties like shape is met be either saying shape is a disguised relational property, or only present properties are intrinsic, or the shapes belong to different things (perdurance).
     From: David Lewis (On the Plurality of Worlds [1986], 4.2)
     A reaction: [compressed] It is certainly implausible to deny that shape is a feature of all physical objects. Or it appears to be. Shapes are hard to pin down at the quantum level. How do you sharply divide moments for the perdurance view? ...
9. Objects / E. Objects over Time / 12. Origin as Essential
I can ask questions which create a context in which origin ceases to be essential [Lewis]
     Full Idea: If I ask how things would be if Saul Kripke had come from no sperm and egg, but was brought by a stork, that makes sense. I create a context that makes my question make sense, which is a context that makes origin not to be essential.
     From: David Lewis (On the Plurality of Worlds [1986], 4.5)
     A reaction: I'm not clear why delivery by a stork doesn't just count as a different origin, and hence it turns out to be essential to Kripke. If Kripke were a necessary being (and he's a good candidate), then he would have no origin.
9. Objects / F. Identity among Objects / 5. Self-Identity
Identity is simple - absolutely everything is self-identical, and nothing is identical to another thing [Lewis]
     Full Idea: Identity is utterly simple and unproblematic. Everything is identical to itself; nothing is ever identical to anything except itself. There is never any problem about what makes something identical to itself; nothing can ever fail to be.
     From: David Lewis (On the Plurality of Worlds [1986], 4.1)
     A reaction: I have great problems with expressing this concept as a thing being 'identical to itself'. I will always say that it 'has an identity'. But then it is problematical, because what constitutes an identity? When do dispersing clouds lose it?
9. Objects / F. Identity among Objects / 6. Identity between Objects
Two things can never be identical, so there is no problem [Lewis]
     Full Idea: There is never any problem about what makes two things identical; two things can never be identical.
     From: David Lewis (On the Plurality of Worlds [1986], 4.1)
     A reaction: This expresses Lewis's preference for usage of the word 'identity', rather than a simple solution. It pays no attention to type-identity, which is an obvious phenomenon. In some sense, it is just obvious that two electrons are 'identical'.
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
Each thing must be in some way unique [Diogenes of Apollonia]
     Full Idea: No one thing among things subject to change can possibly be exactly like any other thing, without becoming the same thing.
     From: Diogenes (Apoll) (fragments/reports [c.440 BCE], B05), quoted by Simplicius - On Aristotle's 'Physics' 153.8
     A reaction: This is said to be the first ever formulation of the principle of identity of indiscernible.
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / b. Conceivable but impossible
The impossible can be imagined as long as it is a bit vague [Lewis]
     Full Idea: Imaginability is a poor criterion of possibility. We can imagine the impossible provided we do not imagine it in perfect detail and all the time.
     From: David Lewis (On the Plurality of Worlds [1986], 1.8)
     A reaction: In general I agree, but Williamson nicely opposes this view. The fact is that we derive most of our understanding of what is possible from imagination. We just have to realise that we can get it wrong, and so must attend to detail.
10. Modality / E. Possible worlds / 1. Possible Worlds / a. Possible worlds
There are no free-floating possibilia; they have mates in a world, giving them extrinsic properties [Lewis]
     Full Idea: There are no free-floating possibilia. Every possibility is part of a world - exactly one world - and thus comes surrounded by worldmates, and fully equipped with extrinsic properties in virtue of its relations to them.
     From: David Lewis (On the Plurality of Worlds [1986], 4.4)
     A reaction: This is a key claim in the possible worlds understanding of modality, contrary to the more common sense and normal language claim that a possibility is an isolated thing.
10. Modality / E. Possible worlds / 1. Possible Worlds / b. Impossible worlds
Possible worlds can contain contradictions if such worlds are seen as fictions [Lewis]
     Full Idea: If worlds were like stories or story-tellers, there would indeed be room for worlds according to which contradictions are true.
     From: David Lewis (On the Plurality of Worlds [1986], 1.2 n3)
     A reaction: Most existing fictions contain tiny contradictions, but we might ask whether that thereby disqualifies them from depicting genuinely 'possible' worlds.
On mountains or in worlds, reporting contradictions is contradictory, so no such truths can be reported [Lewis]
     Full Idea: To tell the alleged truth about contradictory things that happen on a mountain is just contradicting yourself, but you can't tell the truth by contradicting yourself. There is no mountain where contradictions are true, and impossible worlds are no better.
     From: David Lewis (On the Plurality of Worlds [1986], 1.2 n3)
     A reaction: [compressed] He says this works for any 'restricted' domain like a mountain or a real world, but that it wouldn't apply in an unrestricted fictional world.
10. Modality / E. Possible worlds / 1. Possible Worlds / c. Possible worlds realism
For Lewis there is no real possibility, since all possibilities are actual [Oderberg on Lewis]
     Full Idea: Lewis-style modal realism eliminates all real possibility since on his account everything is actual relative to its own world.
     From: comment on David Lewis (On the Plurality of Worlds [1986]) by David S. Oderberg - Real Essentialism 6.2
     A reaction: Since it is possible for me to be in New York and in Chicago, but not both at once, his possibilities have to be kept apart, even though they are actual. I expect my visit to Chicago to remain as only a possibility.
Lewis posits possible worlds just as Quine says that physics needs numbers and sets [Lewis, by Sider]
     Full Idea: Lewis's argument for possible worlds parallels Quine's for the existence of sets: our best overall empirical theory, mathematical physics, quantifies over real numbers, so we have reason to posit real numbers, or the sets to which they may be reduced.
     From: report of David Lewis (On the Plurality of Worlds [1986]) by Theodore Sider - Reductive Theories of Modality 3.6
     A reaction: They both strike me as suspect. Indeed, the extreme implausibility of Lewis's conclusion throws doubt on Quine's original strategy. I'm happy to work with sets and possible worlds, and only worry about ontological commitment at a later stage.
For me, all worlds are equal, with each being actual relative to itself [Lewis]
     Full Idea: For me, all the worlds are on an equal footing in that each is actual relative to itself and none is actual relative to any other.
     From: David Lewis (On the Plurality of Worlds [1986], 3.1)
     A reaction: Lewis says the world we call 'actual' is simply a matter of how our indexicals refer. That sounds the wrong way round to me (as so often with Lewis).
If possible worlds really exist, then they are part of actuality [Sider on Lewis]
     Full Idea: The familiar complaint against Lewis is that if his worlds existed, they'd be part of actuality.
     From: comment on David Lewis (On the Plurality of Worlds [1986]) by Theodore Sider - Writing the Book of the World 11.5
     A reaction: Sider presents that as rather superficial, but it sounds a pretty good objection to me. Lewis would note that only our world has the indexical features which he says pick out actuality. Real possible worlds might lack indexical features?
A world is a maximal mereological sum of spatiotemporally interrelated things [Lewis]
     Full Idea: A world is a maximal mereological sum of spatiotemporally interrelated things.
     From: David Lewis (On the Plurality of Worlds [1986], 1.6)
     A reaction: (I wonder what Lewis's account of space was?) A mereological sum is "the least inclusive thing that includes all the parts" (p.69). It is maximal when all 'worldmates' are parts. But then 'worldmates' are defined as parts, so it threatens circularity.
10. Modality / E. Possible worlds / 1. Possible Worlds / d. Possible worlds actualism
Lewis rejects actualism because he identifies properties with sets [Lewis, by Stalnaker]
     Full Idea: It is the identification of properties with sets that rules out, for Lewis, an actualist account of possible worlds.
     From: report of David Lewis (On the Plurality of Worlds [1986]) by Robert C. Stalnaker - Mere Possibilities 1.1
     A reaction: I suppose the sets which are the properties have to include all the possible red things as well as the actual one. This escapes the renate/cordate problem.
Ersatzers say we have one world, and abstract representations of how it might have been [Lewis]
     Full Idea: The ersatzers say that instead of an incredible plurality of concrete worlds, we can have one world only, and countless abstract entities representing ways that this world might have been.
     From: David Lewis (On the Plurality of Worlds [1986], 3.1)
     A reaction: Put me down as an ersatzer. They seem to be the same as Actualists. Are worlds other possible worlds, or ways 'this world might have been'? Not the same. Does actuality constrain what is possible? (Barcan formula?)
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / a. Nature of possible worlds
Ersatz worlds represent either through language, or by models, or magically [Lewis]
     Full Idea: I distinguish three principal ways ersatz worlds represent: linguistic, in which they are like stories or theories; pictorial, like pictures or isomorphic scale models; or magical, in which it is just their nature to represent.
     From: David Lewis (On the Plurality of Worlds [1986], 3.1)
     A reaction: I think I incline to the 'model' view. The linguistic version means animals can't assess possibilities. I take modelling to be basic to what a mind is, and what a mind is for.
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / b. Worlds as fictions
Linguistic possible worlds need a complete supply of unique names for each thing [Lewis]
     Full Idea: There are two difficulties with Carnap's taking possible worlds as linguistic. Everything must have a name, or our state-descriptions will be silent about nameless things, and nothing may have two names, or we may affirm and deny a predicate of one thing.
     From: David Lewis (On the Plurality of Worlds [1986], 3.2)
     A reaction: The idea of possible worlds as linguistic has no appeal for me, so this problem doesn't surprise or bother me, but it sounds fairly terminal for the project.
Maximal consistency for a world seems a modal distinction, concerning what could be true together [Lewis]
     Full Idea: An ersatz world must be maximally consistent (hence destroyed by an additional sentences), …but that is prima facie a modal distinction: a set of sentences is consistent iff those sentences, as interpreted, could all be true together.
     From: David Lewis (On the Plurality of Worlds [1986], 3.2)
     A reaction: This is indicative of Lewis's motivation for his project, which is to eliminate modal facts from the world. Only a vast multitude of non-modal concrete worlds can satisfy all the contraints. Cf many-worlds quantum mechanics for non-locality.
Linguistic possible worlds have problems of inconsistencies, no indiscernibles, and vocabulary [Lewis]
     Full Idea: Linguistic representations of possible worlds have three problems: some descriptions are inconsistent (which worlds cannot be); we cannot have indiscernible descriptions (though some worlds might be so); and descriptions are limited by vocabulary.
     From: David Lewis (On the Plurality of Worlds [1986], 3.2)
     A reaction: Lewis is wonderful at getting problems clearly on the table. I take the idea of possible worlds as linguistic entities to be a non-starter, because (as usual) animals do it too, when they think of possibilities, which even the dimmest ones must do.
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / c. Worlds as propositions
If sets exist, then defining worlds as proposition sets implies an odd distinction between existing and actual [Jacquette on Lewis]
     Full Idea: If sets exist, then the conventional concept of a logically possible world as a proposition set requires a counterintuitive distinction between existence and actuality, between what exists and what is actual.
     From: comment on David Lewis (On the Plurality of Worlds [1986]) by Dale Jacquette - Ontology Ch.2
     A reaction: This pinpoints the obvious difficulty that most people have with Lewis's claim that possible worlds exist. Russell's claim that universals 'subsist' (Idea 5409) is a similar attempt to have two different sorts of existence in your ontology.
10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
A counterpart in a possible world is sufficiently similar, and more similar than anything else [Lewis, by Mautner]
     Full Idea: 'Jack could have been taller' implies a different Jack in a different world, so Lewis defines a counterpart in a possible world as an individual sufficiently similar to Jack, and more similar to Jack than anything else in that world.
     From: report of David Lewis (On the Plurality of Worlds [1986]) by Thomas Mautner - Penguin Dictionary of Philosophy p.115
     A reaction: If we say something like "I could have been twins" or "I could have been a genius" in another world, it would need an odd concept of my personal identity for it to remain identical in those counterfactual situations. Lewis has a point.
In counterpart theory 'Humphrey' doesn't name one being, but a mereological sum of many beings [Lewis]
     Full Idea: For the counterpart theorist, the trick is to say that 'Humphrey' names not the Humphrey of our world, and not the Humphrey of another, but rather the trans-world individual who is the mereological sum of all those local Humphreys.
     From: David Lewis (On the Plurality of Worlds [1986], 4.1)
     A reaction: On Lewis's perdurantism Humphrey is a 'spacetime worm' across his lifetime. Now we are adding all the possible Humphreys to the sum. I'm losing track of Humphrey's shape.
The counterpart relation is sortal-relative, so objects need not be a certain way [Lewis, by Merricks]
     Full Idea: Lewis takes the counterpart relation to be sortal-relative, so he (no less than Quine) denies that objects, qua existing, are necessarily a certain way.
     From: report of David Lewis (On the Plurality of Worlds [1986]) by Trenton Merricks - Truth and Ontology 5.III n10
     A reaction: Does this mean that there could be two different versions of the same possible world (certainly not!), or that worlds are entirely created by our concepts rather than by what is actually possible.
Why should statements about what my 'counterpart' could have done interest me? [Mautner on Lewis]
     Full Idea: If I only have counterparts in possible worlds who are not identical to me, statements about what I could have done will seem irrelevant to me, because they will be about someone else.
     From: comment on David Lewis (On the Plurality of Worlds [1986]) by Thomas Mautner - Penguin Dictionary of Philosophy p.115
     A reaction: We might rephrase the statement as "I could have been the person who did x". Presumably my counterpart is not just any stranger, but someone I could have been. "I could have been a brick" - now that seems irrelevant to me!
10. Modality / E. Possible worlds / 3. Transworld Objects / d. Haecceitism
Extreme haecceitists could say I might have been a poached egg, but it is too remote to consider [Lewis, by Mackie,P]
     Full Idea: Lewis's strategy for defending extreme haecceitism is that supposed impossibilities (that I might have been a poached egg) could be reconstrued as genuine possibilities that are so remote from reality that they are ignored.
     From: report of David Lewis (On the Plurality of Worlds [1986], 239-) by Penelope Mackie - How Things Might Have Been 9.3
     A reaction: Not a promising route. Wiggins asks: if you think I could have been a poached egg, start by defining more precisely this 'I' to which we are referring. The definition will blatantly exclude any possibility of my poachedegghood.
Haecceitism implies de re differences but qualitative identity [Lewis]
     Full Idea: If two worlds differ in what they represent de re concerning some individual, but do not differ qualitatively in any way, I shall call that a haecceitist difference. Haecceitism, then, says there are at least some haecceitist differences between worlds.
     From: David Lewis (On the Plurality of Worlds [1986], 4.4)
     A reaction: Lewis bases this view on Kaplan. My brief summary of this is that 'identity may be hidden'. If all electrons are different, what distinguishes them?
Extreme haecceitism says you might possibly be a poached egg [Lewis]
     Full Idea: The most extreme version of haecceitism says that anything could possibly have any qualitative character; for instance, there is a world according to which you are a poached egg.
     From: David Lewis (On the Plurality of Worlds [1986], 4.4)
     A reaction: Presumably a plausible haecceitist view would have to be combined with essentialism, given that the possibility that I might be a poached egg is beyond my intuitive grasp.
12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
Start a thesis with something undisputable [Diogenes of Apollonia]
     Full Idea: In starting any thesis, it seems to me, one should put forward as one's point of departure something incontrovertible.
     From: Diogenes (Apoll) (fragments/reports [c.440 BCE], B01), quoted by Diogenes Laertius - Lives of Eminent Philosophers 09.57
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / a. Qualities in perception
If properties were qualities without dispositions, they would be undetectable [Heil]
     Full Idea: A pure quality, a property altogether lacking in dispositionality, would be undetectable and would, in one obvious sense, make no difference to its possessor.
     From: John Heil (From an Ontological Point of View [2003], 11.4)
     A reaction: This seems to be a very forceful and simple reason why we cannot view properties simply as qualities of things. Heil wants properties to be dispositions and qualities; personally I would vote for them just being dispositions or powers.
Can we distinguish the way a property is from the property? [Heil]
     Full Idea: It is not clear to me that we easily distinguish ways a property is from the property itself.
     From: John Heil (From an Ontological Point of View [2003], 11.6)
     A reaction: To defend properties as qualities, he is confusing ontology and epistemology. Presumably he means by 'ways a property is' what I would prefer to call 'ways a property seems to be'. I don't believe a smell is simply what it seems to be.
Properties don't possess ways they are, because that just is the property [Heil]
     Full Idea: Objects possess properties, but I am sceptical of the idea that properties possess properties; just as a property is a way some object is, a property of a property would be a way a property is, but that is just the property itself.
     From: John Heil (From an Ontological Point of View [2003], 12.1)
     A reaction: This is quite a good defence of the idea that properties are qualities as well as dispositions. However, if we make the qualities of properties into secondary qualities, and the dispositions into primary qualities, the absurdity melts away.
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / b. Primary/secondary
Objects only have secondary qualities because they have primary qualities [Heil]
     Full Idea: Secondary qualities are not distinct from primary qualities: an object's possession of a given secondary quality is a matter of its possession of certain complex primary qualities.
     From: John Heil (From an Ontological Point of View [2003], 17.3)
     A reaction: The bottom line here is that, if essentialism is right, colours are not properties at all (see Idea 5456). Heil wants to subsume secondary properties within primary properties. I think we should sharply distinguish them.
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / d. Secondary qualities
Secondary qualities are just primary qualities considered in the light of their effect on us [Heil]
     Full Idea: Secondary qualities are just ordinary properties - roughly, Locke's primary qualities - considered in the light of their effects on us.
     From: John Heil (From an Ontological Point of View [2003], 14.10)
     A reaction: Unconvincing. If they only acquire their ontological status as primary qualities if they have to be considered in relation to something (us), then that is not a primary quality.
Colours aren't surface properties, because of radiant sources and the colour of the sky [Heil]
     Full Idea: Theories that take colours to be properties of the surfaces of objects have difficulty accounting for a host of phenomena including coloured light emitted by radiant sources and so-called film colours (the colour of the sky, for instance).
     From: John Heil (From an Ontological Point of View [2003], 17.4)
     A reaction: Personally I never thought that colours might be actual properties of surfaces, but it is nice to have spelled out a couple of instances that make it very implausible. Neon and sodium lights I take to be examples of the first case.
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / e. Primary/secondary critique
Treating colour as light radiation has the implausible result that tomatoes are not red [Heil]
     Full Idea: Theories that tie colours to features of light radiation deal with radiant and diffused colours, but yield implausible results for objects; tomatoes are not red, on such a view, but merely reflect red light.
     From: John Heil (From an Ontological Point of View [2003], 17.4)
     A reaction: I see absolutely no problem with the philosophical denial that tomatoes are actually red, while continuing to use 'red' of tomatoes in the normal way. When we analyse our processes of knowledge acquisition, we must give up 'common sense'.
12. Knowledge Sources / B. Perception / 6. Inference in Perception
Perception must be an internal matter, because we can fail to perceive when we are preoccupied [Diogenes of Apollonia, by Theophrastus]
     Full Idea: That it is the inner air that perceives, as being a fragment of the god, is shown by the fact that often when our minds are preoccupied with other matters we fail to see or hear.
     From: report of Diogenes (Apoll) (fragments/reports [c.440 BCE], A19) by Theophrastus - On the Senses 42
13. Knowledge Criteria / C. External Justification / 2. Causal Justification
General causal theories of knowledge are refuted by mathematics [Lewis]
     Full Idea: Causal accounts of knowledge are all very well in their place, but if they are put forward as general theories, then mathematics refutes them.
     From: David Lewis (On the Plurality of Worlds [1986], 2.4)
     A reaction: You might have some sort of notion of an abstraction from causation which mimicked it in the mathematics case. Lots of things seem to be 'forced' in mathematics. Call it 'ersatz causation'. Necessities are enforcers.
13. Knowledge Criteria / E. Relativism / 6. Relativism Critique
If the world is just texts or social constructs, what are texts and social constructs? [Heil]
     Full Idea: For those who regard the world as text or a social construct, are texts and social constructs real entities? If they are, what are they?
     From: John Heil (From an Ontological Point of View [2003], 20.6)
     A reaction: A nice turn-the-tables question. The oldest attacks of all on scepticism and relativism consist of showing that the positions themselves rest on knowledge or truth. Nietzsche may be the best model for relativists. E.g. Idea 4420.
14. Science / B. Scientific Theories / 1. Scientific Theory
If the world is theory-dependent, the theories themselves can't be theory-dependent [Heil]
     Full Idea: If the world is somehow theory-dependent, this implies, on pain of a regress, that theories are not theory-dependent.
     From: John Heil (From an Ontological Point of View [2003], 06.4)
     A reaction: I am not sure where this puts the ontology of theories, but this is a nice question, of a type which never seems to occur to your more simple-minded relativist.
14. Science / B. Scientific Theories / 2. Aim of Science
Science is sometimes said to classify powers, neglecting qualities [Heil]
     Full Idea: The sciences are sometimes said to be in the business of identifying and classifying powers; the mass of an electron, its spin and charge, could be regarded as powers possessed by the electron; science is silent on an electron's qualities.
     From: John Heil (From an Ontological Point of View [2003], 11.2)
     A reaction: Heil raises the possibility that qualities are real, despite the silence of science; he wants colour to be a real quality. I like the simpler version of science. Qualities are the mental effects of powers; there exist substances, powers and effects.
14. Science / C. Induction / 2. Aims of Induction
Induction is just reasonable methods of inferring the unobserved from the observed [Lewis]
     Full Idea: I use the word 'induction' broadly, to cover all the methods we deem reasonable for forming beliefs about the unobserved parts of our world on the basis of experience with the observed parts.
     From: David Lewis (On the Plurality of Worlds [1986], 2.5)
     A reaction: Good. Attempts to be precise about it seem to be hopeless and invite paradoxes. Personally I just define it as 'learning from experience', because that makes what we do continuous with the behaviour of other sensible animals.
14. Science / C. Induction / 5. Paradoxes of Induction / a. Grue problem
To just expect unexamined emeralds to be grue would be totally unreasonable [Lewis]
     Full Idea: Some beliefs are just unreasonable in a strong sense. Think of the man who, for no special reason, expects unexamined emeralds to be grue.
     From: David Lewis (On the Plurality of Worlds [1986], 1.4)
     A reaction: This is a nice converse way of seeing the point that 'grue' is such an totally artificial predicate. I still say that the most illuminating point is that grue is not a colour, so seeing a grue thing is no confirmation at all.
14. Science / D. Explanation / 2. Types of Explanation / g. Causal explanations
An explanation tells us how an event was caused [Lewis]
     Full Idea: An explanation, I think, is an account of etiology: it tells us something about how an event was caused.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: Will this cover mathematical explanations? Numbers would have to have causal powers.
Often explanaton seeks fundamental laws, rather than causal histories [Lewis]
     Full Idea: Sometimes the pursuit of explanation is more the pursuit of unified and general fundamental laws than of information about the causal histories of events.
     From: David Lewis (On the Plurality of Worlds [1986], 2.7)
     A reaction: It is hard to disagree, given the 'sometimes'. I don't think that Newton's Law of Gravity (say), with its lovely equation, actually explained anything at all about gravity. Finding the law closes the quest for an accurate description of what happens.
14. Science / D. Explanation / 2. Types of Explanation / j. Explanations by reduction
One form of explanation is by decomposition [Heil]
     Full Idea: One form of explanation is by decomposition.
     From: John Heil (From an Ontological Point of View [2003], 19.8)
     A reaction: This is a fancy word for taking it apart, presumably to see how it works, which implies a functional explanation, rather than to see what it is made of, which seeks an ontological explanation. Simply 'decomposing' something wouldn't in itself explain.
14. Science / D. Explanation / 2. Types of Explanation / l. Probabilistic explanations
If the well-ordering of a pack of cards was by shuffling, the explanation would make it more surprising [Lewis]
     Full Idea: Suppose you find in a hotel room a pack of cards in exactly standard order. Not surprising - maybe it's a new deck, or someone arranged them. Not so. They got that way by being fairly shuffled. The explanation would make the explanandum more surprising.
     From: David Lewis (On the Plurality of Worlds [1986], 2.7)
     A reaction: [compressed] A lovely Lewisian example, that instantly makes big trouble for the (implausible) view that a cause is something which increases the likelihood of a thing.
15. Nature of Minds / B. Features of Minds / 4. Intentionality / b. Intentionality theories
Dispositionality provides the grounding for intentionality [Heil]
     Full Idea: Dispositionality provides the grounding for intentionality.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: This is a view with which I am sympathetic, though I am not sure if it explains anything. It would be necessary to identify a disposition of basic matter that could be built up into the disposition of a brain to think about things.
Intentionality now has internalist (intrinsic to thinkers) and externalist (environment or community) views [Heil]
     Full Idea: Nowadays philosophers concerned with intentionality divide into two camps. Internalists epitomise a traditional approach to thought, as intrinsic features of thinkers; externalists say it depends on contextual factors (environment or community).
     From: John Heil (From an Ontological Point of View [2003], 18.2)
     A reaction: This is basic to understanding modern debates (those that grow out of Putnam's Twin Earth). Externalism is fashionable, but I am reluctant to shake off my quaint internalism. Start by separating strict and literal meaning from speaker's meaning.
15. Nature of Minds / B. Features of Minds / 5. Qualia / c. Explaining qualia
Qualia are not extra appendages, but intrinsic ingredients of material states and processes [Heil]
     Full Idea: Properties of conscious experience, the so-called qualia, are not dangling appendages to material states and processes but intrinsic ingredients of those states and processes.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: Personally I am inclined to the view that qualia are intrinsic to the processes and NOT to the 'states'. Heil must be right, though. I am sure qualia are not just epiphenomena - they are too useful.
17. Mind and Body / A. Mind-Body Dualism / 7. Zombies
Philosophers' zombies aim to show consciousness is over and above the physical world [Heil]
     Full Idea: Philosophers' zombies (invented by Robert Kirk) differ from the zombies of folklore; they are intended to make clear the idea that consciousness is an addition of being, something 'over and above' the physical world.
     From: John Heil (From an Ontological Point of View [2003], 20.1 n1)
     A reaction: The famous defender of zombies is David Chalmers. You can't believe in zombies if you believe (as I do) that 'the physical entails the mental'. Could there be redness without something that is red? If consciousness is extra, what is conscious?
Zombies are based on the idea that consciousness relates contingently to the physical [Heil]
     Full Idea: The possibility of zombies is founded on the idea that consciousness is related contingently to physical states and processes.
     From: John Heil (From an Ontological Point of View [2003], 20.3)
     A reaction: The question is, how do you decide whether the relationship is contingent or necessary? Hence the interest in whether conceivability entails possibility. Kripke attacks the idea of contingent identity, pointing towards necessity, and away from zombies.
Functionalists deny zombies, since identity of functional state means identity of mental state [Heil]
     Full Idea: Functionalists deny that zombies are possible since states of mind (including conscious states) are purely functional states. If two agents are in the same functional state, regardless of qualitative difference, they are in the same mental state.
     From: John Heil (From an Ontological Point of View [2003], 20.5)
     A reaction: In its 'brief' form this idea begins to smell of tautology. Only the right sort of functional state would entail a mental state, and how else can that functional state be defined, apart from its leading to a mental state?
17. Mind and Body / C. Functionalism / 1. Functionalism
Functionalists say objects can be the same in disposition but differ in quality [Heil]
     Full Idea: A central tenet of functionalism is that objects can be dispositionally indiscernible but differ qualitatively as much as you please.
     From: John Heil (From an Ontological Point of View [2003], 11.3)
     A reaction: This refers to the multiple realisability of functions. Presumably we reconcile essentialism with the functionalist view by saying that dispositions result from combinations of qualities. A unique combination of qualities will necessitate a disposition.
17. Mind and Body / C. Functionalism / 8. Functionalism critique
Functionalism cannot explain consciousness just by functional organisation [Heil]
     Full Idea: Functionalism has been widely criticized on the grounds that it is implausible to think that functional organization alone could suffice for conscious experience.
     From: John Heil (From an Ontological Point of View [2003], 20.2)
     A reaction: He cites Block's 'Chinese Mind' as an example. The obvious reply is that you can't explain consciousness with a lump of meat, or with behaviour, or with an anomalous property, or even with a non-physical substance.
17. Mind and Body / D. Property Dualism / 6. Mysterianism
The 'explanatory gap' is used to say consciousness is inexplicable, at least with current concepts [Heil]
     Full Idea: The expression 'explanatory gap' was coined by Joseph Levine in 1983. McGinn and Chalmers have invoked it in defence of the view that consciousness is physically inexplicable, and Nagel that it is inexplicable given existing conceptual resources.
     From: John Heil (From an Ontological Point of View [2003], 19.8 n14)
     A reaction: Coining a few concepts isn't going to help, but discovering more about the brain might. With computer simulations we will 'see' more of the physical end of thought. Psychologists may break thought down into physically more manageable components.
17. Mind and Body / E. Mind as Physical / 1. Physical Mind
The older Diogenes said the soul is air, made of the smallest particles [Diogenes of Apollonia]
     Full Idea: Diogenes [of Apollonia] took the soul to be air, thnking that of all things air is composed of the smallest particles and is a starting point.
     From: Diogenes (Apoll) (fragments/reports [c.440 BCE], DK 64), quoted by Aristotle - De Anima 405a21
     A reaction: This suggests that Diogenes of Apollonia was an atomist, if the soul is made of particles. See also Met 984a5, which says Anaxagoras had the same view.
17. Mind and Body / E. Mind as Physical / 5. Causal Argument
If a car is a higher-level entity, distinct from its parts, how could it ever do anything? [Heil]
     Full Idea: If we regard a Volvo car as a higher-level entity with its own independent reality, something distinct from its constituents (arranged in particular ways and variously connected to other things), we render mysterious how Volvos could do anything at all.
     From: John Heil (From an Ontological Point of View [2003], 02.3)
     A reaction: This seems to me perhaps the key reason why we have to be reductionists. The so-called 'bridge laws' from mind to brain are not just needed to explain the mind, they are also essential to show how a mind would cause behaviour.
17. Mind and Body / E. Mind as Physical / 7. Anti-Physicalism / b. Multiple realisability
Multiple realisability is actually one predicate applying to a diverse range of properties [Heil]
     Full Idea: Cases of multiple realisability are typically cases in which some predicate ('is red', 'is in pain') applies to an object in virtue of that object's possession of any of a diverse range of properties.
     From: John Heil (From an Ontological Point of View [2003], 14.8)
     A reaction: If the properties are diverse, why does one predicate apply to them? I take it that in the case of the pain, the predicate is ambiguous in applying to the behaviour or the phenomenal property. Same behaviour is possible with many qualia.
18. Thought / C. Content / 6. Broad Content
Externalism is causal-historical, or social, or biological [Heil]
     Full Idea: Some externalists focus on causal-historical connections, others emphasise social matters (especially thinkers' linguistic communities), still others focus on biological function.
     From: John Heil (From an Ontological Point of View [2003], 18.5 n6)
     A reaction: Helpful. The social view strikes me as the one to take most seriously (allowing for contextual views of justification, and for the social role of experts). The problem is to combine the social view with realism and a robust view of truth.
18. Thought / C. Content / 7. Narrow Content
Intentionality is based in dispositions, which are intrinsic to agents, suggesting internalism [Heil]
     Full Idea: I suggest that intentionality is grounded in the dispositionalities of agents. Dispositions are intrinsic to agents, so this places me on the side of the internalists and against the externalists.
     From: John Heil (From an Ontological Point of View [2003], 18.4)
     A reaction: I think this is a key idea, and the right view. The key question is whether we see intentionality as active or passive. The externalist view seems to see the brain as a passive organ which the world manipulates. If the brain is active, what is it doing?
18. Thought / E. Abstraction / 1. Abstract Thought
Abstraction is usually explained either by example, or conflation, or abstraction, or negatively [Lewis]
     Full Idea: Abstraction is usually explained in one of four ways: the Way of Example (cf. donkeys and numbers), the Way of Conflation (same as sets), the Negative Way (non-spatial and non-causal) or the Way of Abstraction (incomplete descriptions).
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: [Compressed; a footnote dismisses Dummett's fifth way] Example has blurred boundaries, and explains nothing. Gerrymandered sets don't produce concepts. Negative accounts explain nothing. So it's the Way of Abstraction!
18. Thought / E. Abstraction / 3. Abstracta by Ignoring
The Way of Abstraction says an incomplete description of a concrete entity is the complete abstraction [Lewis]
     Full Idea: The Way of Abstraction says abstract entities are abstractions from concrete entities; they result from somehow subtracting specificity, so that an incomplete description of the original concrete entity is a complete description of the abstraction.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: Defined like this, it rather looks as if abstractions would be entirely verbal - which may well be the correct situation, except that higher animals seem capable of minimal levels of abstraction. This Way is denigrated by Frege and Geach.
18. Thought / E. Abstraction / 4. Abstracta by Example
The Way of Example compares donkeys and numbers, but what is the difference, and what are numbers? [Lewis]
     Full Idea: The Way of Example says concrete entities are things like donkeys and puddles, but abstract entities are things like numbers. That gives us little guidance. There are no uncontroversial accounts of numbers, and donkeys and number differ in too many ways.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: That demolishes that fairly swiftly. It may be unfair to demand an agreed account of numbers, but the respect(s) in which donkeys and numbers differ needs to be spelled out before anything useful has been said.
18. Thought / E. Abstraction / 6. Abstracta by Conflation
Abstracta can be causal: sets can be causes or effects; there can be universal effects; events may be sets [Lewis]
     Full Idea: Is it true that sets or universals cannot enter into causal interaction? Why can't we say that a set of things causes something, or something causes a set of effects? Or positive charge has characteristic effects? Or an event is a sort of set?
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: This idea, and 8902, form a devastating critique of attempts to define abstraction in a purely negative way, as non-spatial and non-causal. Only a drastic revision of widely held views about sets, universals and events could save that account.
If abstractions are non-spatial, then both sets and universals seem to have locations [Lewis]
     Full Idea: If abstract entities are not located, then a set of things does seem to have a location, though perhaps a divided one; and universals, if they are wholly present in each particular, are where their instances are, so negation can't define abstraction.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: He admits that non-spatial accounts of sets and universals are possible, but the jury is out on both of them, and more cautious theories, even if they are realist, will give them both locations. A good argument.
If universals or tropes are parts of things, then abstraction picks out those parts [Lewis]
     Full Idea: A theory of non-spatiotemporal parts of things, whether recurring universals or non-recurring tropes, makes good sense of some abstractions. Unit negative charge is a universal common to particles, and an abstraction by being part of them.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: He cautiously refers to 'some' abstractions. It is one of Donald Williams's proud boasts concerning his trope theory that it will handle this problem well. I'm not sure that we should be saying that abstractions are actually concrete bits of things.
If we can abstract the extrinsic relations and features of objects, abstraction isn't universals or tropes [Lewis]
     Full Idea: Why can't we abstract a highly extrinsic aspect of something, say its surname, or its spatiotemporal location, or its role in a causal network, or its role in some body of theory? But these are unsuitable candidates for being genuine universals or tropes.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: (This is a criticism of the proposal in Idea 8905) Obviously we can abstract such things. In particular the role in a causal network is a function, which is a central example of an abstract idea. Russell keeps reminding us that relations are universals.
18. Thought / E. Abstraction / 7. Abstracta by Equivalence
The abstract direction of a line is the equivalence class of it and all lines parallel to it [Lewis]
     Full Idea: We can abstract the direction of a line by taking the direction as the equivalence class of that line and all lines parallel to it. There is no subtraction of detail, but a multiplication of it; by swamping it, the specifics of the original line get lost.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: You can ask how wide a line is, but not how wide a direction is, so a detail IS being subtracted. I don't see how you can define the concept of a banana by just saying it is 'every object which is equivalent to a banana'. 'Parallel' is an abstraction.
For most sets, the concept of equivalence is too artificial to explain abstraction [Lewis]
     Full Idea: Most sets cannot be regarded as abstractions by equivalence: most sets are equivalence classes only under thoroughly artificial equivalence. (And the empty set is not an equivalence class at all).
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: [Recorded for further investigation..] My intuitions certainly cry out against such a thin logical notion giving a decent explanation of such a rich activity as abstraction.
18. Thought / E. Abstraction / 8. Abstractionism Critique
We can't account for an abstraction as 'from' something if the something doesn't exist [Lewis]
     Full Idea: We cannot really be talking about the things whence an abstraction-like entity is abstracted if there are no such things.
     From: David Lewis (On the Plurality of Worlds [1986], 3.3)
     A reaction: Sounds like a killer blow, but I don't think so. I can't think of a concept which doesn't have a possible basis in reality, assuming that it might be a complex assemblage of abstracted components.
19. Language / A. Nature of Meaning / 2. Meaning as Mental
The Picture Theory claims we can read reality from our ways of speaking about it [Heil]
     Full Idea: The theory of language which I designate the 'Picture Theory' says that language pictures reality in roughly the sense that we can 'read off' features of reality from our ways of speaking about it.
     From: John Heil (From an Ontological Point of View [2003], 03.2)
     A reaction: Heil, quite rightly, attacks this view very strongly. I think of it as the great twentieth century philosophical heresy, that leads to shocking views like relativism and anti-realism.
19. Language / A. Nature of Meaning / 7. Meaning Holism / c. Meaning by Role
A particular functional role is what gives content to a thought [Lewis]
     Full Idea: Anything that is a thinker at all has a thought with a certain content in virtue of being in a state which occupies a certain functional role.
     From: David Lewis (On the Plurality of Worlds [1986], 2.3)
     A reaction: So often Lewis seems to get things the wrong way round. Maybe if you invert his entire (fabulously consistent) philosophy, you get the right answer? I take the content to be what makes the role possible.
19. Language / D. Propositions / 2. Abstract Propositions / b. Propositions as possible worlds
A proposition is a set of entire possible worlds which instantiate a particular property [Lewis]
     Full Idea: I identify propositions with certain properties - namely, with those that are instantiated only by entire possible worlds. Then if properties generally are the sets of their instances, a proposition is a set of possible worlds.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: I don't get this. How can the proposition that tomatoes are edible be an entire set of possible worlds? The proposition seems to be about tomatoes, and nothing else. Should we talk of 'possibilities', rather than of 'possible worlds'?
A proposition is the property of being a possible world where it holds true [Lewis]
     Full Idea: I identify propositions with properties that are instantiated only by entire possible worlds. If properties are the sets of their instances, a proposition is a set of possible worlds. A proposition is the property of being a world where it holds.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: This is so far away from my concept of a proposition (as a truth-evaluable representational mental event) that I struggle to compute it. So the proposition that I am sitting here is the property of 'being the actual world'. Eh?
Propositions can't have syntactic structure if they are just sets of worlds [Lewis]
     Full Idea: If it is central to 'proposition' that there be quasi-syntactic structure, so that there are subject-predicate, or negative, or conjunctive, or quantified propositions, then sets of possible worlds will not do.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: He proposes 'more complicated set-theoretic constructions out of possibilia' instead. I am very much committed to propositions having quasi-syntactic structure.
If propositions are states of affairs or sets of possible worlds, these lack truth values [Heil]
     Full Idea: When pressed, philosophers will describe propositions as states of affairs or sets of possible worlds. But wait! Neither sets of possible worlds nor states of affairs - electrons being negatively charged, for instance - have truth values.
     From: John Heil (From an Ontological Point of View [2003], Intro)
     A reaction: I'm not sure that I see a problem. A pure proposition, expressed as, say "there is a giraffe on the roof" only acquires a truth value at the point where you assert it or believe it. There IS a possible world where there is a giraffe on the roof.
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / a. Final purpose
Diogenes of Apollonia offered the first teleological account of cosmology [Diogenes of Apollonia, by Robinson,TM]
     Full Idea: Credit for the first clear assertion of teleological explanation in cosmology goes to Diogenes of Apollonia, for whom air is the divine and intelligent ground of the real and disposes things in the best possible way.
     From: report of Diogenes (Apoll) (fragments/reports [c.440 BCE]) by T.M. Robinson - Classical Cosmology (frags)
     A reaction: The first teleological explanation seems to be based on a conscious mind. There also emerges the possibility of some sort of non-conscious teleology, closer to the laws of physics than to God.
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / c. Ultimate substances
Air is divine, because it is in and around everything, and arranges everything [Diogenes of Apollonia]
     Full Idea: Air in itself seems to me to be God and to reach everywhere and to arrange everything and to be in everything.
     From: Diogenes (Apoll) (fragments/reports [c.440 BCE], B05), quoted by Simplicius - On Aristotle's 'Physics' 152.22-
     A reaction: So water and fire and air have been offered as the ultimate explanans, though no one seems to offer earth, which is too grubby and miserable (and was denied a Form by Plato). 'Air is God' could ground a nice modern religious sect.
Everything is ultimately a variation of one underlying thing [Diogenes of Apollonia]
     Full Idea: It seems to me that all existing things are created by the alteration of the same thing, and are the same thing.
     From: Diogenes (Apoll) (fragments/reports [c.440 BCE], B02), quoted by Simplicius - On Aristotle's 'Physics' 151.31-
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / f. Ancient elements
Plants and animals can only come into existence if something fixes their species [Diogenes of Apollonia]
     Full Idea: No plant could grow out of the earth, and no animal or any other thing could come into being, unless it were so compounded as to be the same.
     From: Diogenes (Apoll) (fragments/reports [c.440 BCE], B02), quoted by Simplicius - On Aristotle's 'Physics' 151.31-
Things must retain their essential nature during change, or mixing would be impossible [Diogenes of Apollonia]
     Full Idea: If any existing thing were different in its own essential nature, and were not the same thing which was transformed in many ways and changed, in no way could things mix with one another.
     From: Diogenes (Apoll) (fragments/reports [c.440 BCE], B02), quoted by Simplicius - On Aristotle's 'Physics' 151.31-
26. Natural Theory / C. Causation / 9. General Causation / b. Nomological causation
The standard view is that causal sequences are backed by laws, and between particular events [Heil]
     Full Idea: The notion that every causal sequence if backed by a law, like the idea that causation is a relation among particular events, forms a part of philosophy's Humean heritage.
     From: John Heil (From an Ontological Point of View [2003], 04.3)
     A reaction: This nicely pinpoints a view that needs to come under attack. I take the view that there are no 'laws' - other than the regularities in behaviour that result from the interaction of essential dispositional properties. Essences don't need laws.
26. Natural Theory / C. Causation / 9. General Causation / c. Counterfactual causation
Causation is when at the closest world without the cause, there is no effect either [Lewis]
     Full Idea: If it is the case at world W that if event C had not occurred, E would not have occurred either, then the counterfactual means that at the closest worlds to W at which C does not occur, E does not occur either.
     From: David Lewis (On the Plurality of Worlds [1986], 1.6)
     A reaction: This is a very Humean account, though updated, which sees nothing more to causation than transworld regularities. To me that is just describing the evidence for causation, not giving an account of it (even if the latter is impossible).
27. Natural Reality / D. Time / 1. Nature of Time / g. Growing block
It is quite implausible that the future is unreal, as that would terminate everything [Lewis]
     Full Idea: It is hard to believe that any philosopher means it when they say the future is unreal. If anyone is right that there is no future, that moment is their last, and it is the end of everything.
     From: David Lewis (On the Plurality of Worlds [1986], 4.2)
     A reaction: A bit simplistic. I might say 'there will be a future time, but it doesn't exist now'. That's the peculiar thing about time. If I say New York doesn't exist, then clearly I can't visit it. The London 2012 Olympic Stadium is going to exist.
27. Natural Reality / F. Chemistry / 2. Modern Elements
The real natural properties are sparse, but there are many complex properties [Heil]
     Full Idea: I am sympathetic to the idea that the real properties are 'sparse'; ...but if, in counting kinds of property, we include complex properties as well as simple properties, the image of sparseness evaporates.
     From: John Heil (From an Ontological Point of View [2003], 13.4)
     A reaction: This seems right to me, and invites the obvious question of which are the sparse real properties. Presumably we let the physicists tell us that, though Heil wants to include qualities like phenomenal colour, which physicists ignore.