111 ideas
| 23890 | For Plato true wisdom is supernatural [Plato, by Weil] |
| Full Idea: It is evident that Plato regards true wisdom as something supernatural. | |
| From: report of Plato (works [c.375 BCE]) by Simone Weil - God in Plato p.61 | |
| A reaction: Taken literally, I assume this is wrong, but we can empathise with the thought. Wisdom has the feeling of rising above the level of mere knowledge, to achieve the overview I associate with philosophy. |
| 3060 | Plato never mentions Democritus, and wished to burn his books [Plato, by Diog. Laertius] |
| Full Idea: Plato, who mentions nearly all the ancient philosophers, nowhere speaks of Democritus; he wished to burn all of his books, but was persuaded that it was futile. | |
| From: report of Plato (works [c.375 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.7.8 |
| 16227 | Philosophers are good at denying the obvious [Hawley] |
| Full Idea: Philosophers are skilled at resisting even the most inviting thoughts. | |
| From: Katherine Hawley (How Things Persist [2001], 5) | |
| A reaction: Not exactly 'despair', but it does show how far philosophers are able to stray from common sense. Monads, real possible worlds, real sets… Thomas Reid, the philosopher of common sense, might be the antidote. |
| 23891 | Two contradictories force us to find a relation which will correlate them [Plato, by Weil] |
| Full Idea: Where contradictions appear there is a correlation of contraries, which is relation. If a contradiction is imposed on the intelligence, it is forced to think of a relation to transform the contradiction into a correlation, which draws the soul higher. | |
| From: report of Plato (works [c.375 BCE]) by Simone Weil - God in Plato p.70 | |
| A reaction: A much better account of the dialectic than anything I have yet seen in Hegel. For the first time I see some sense in it. A contradiction is not a falsehood, and it must be addressed rather than side-stepped. A kink in the system, that needs ironing. |
| 10987 | Three traditional names of rules are 'Simplification', 'Addition' and 'Disjunctive Syllogism' [Read] |
| Full Idea: Three traditional names for rules are 'Simplification' (P from 'P and Q'), 'Addition' ('P or Q' from P), and 'Disjunctive Syllogism' (Q from 'P or Q' and 'not-P'). | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 11004 | Necessity is provability in S4, and true in all worlds in S5 [Read] |
| Full Idea: In S4 necessity is said to be informal 'provability', and in S5 it is said to be 'true in every possible world'. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.4) | |
| A reaction: It seems that the S4 version is proof-theoretic, and the S5 version is semantic. |
| 11018 | There are fuzzy predicates (and sets), and fuzzy quantifiers and modifiers [Read] |
| Full Idea: In fuzzy logic, besides fuzzy predicates, which define fuzzy sets, there are also fuzzy quantifiers (such as 'most' and 'few') and fuzzy modifiers (such as 'usually'). | |
| From: Stephen Read (Thinking About Logic [1995], Ch.7) |
| 11011 | Same say there are positive, negative and neuter free logics [Read] |
| Full Idea: It is normal to classify free logics into three sorts; positive free logics (some propositions with empty terms are true), negative free logics (they are false), and neuter free logics (they lack truth-value), though I find this unhelpful and superficial. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.5) |
| 11020 | Realisms like the full Comprehension Principle, that all good concepts determine sets [Read] |
| Full Idea: Hard-headed realism tends to embrace the full Comprehension Principle, that every well-defined concept determines a set. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.8) | |
| A reaction: This sort of thing gets you into trouble with Russell's paradox (though that is presumably meant to be excluded somehow by 'well-defined'). There are lots of diluted Comprehension Principles. |
| 10986 | Not all validity is captured in first-order logic [Read] |
| Full Idea: We must recognise that first-order classical logic is inadequate to describe all valid consequences, that is, all cases in which it is impossible for the premisses to be true and the conclusion false. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: This is despite the fact that first-order logic is 'complete', in the sense that its own truths are all provable. |
| 10972 | The non-emptiness of the domain is characteristic of classical logic [Read] |
| Full Idea: The non-emptiness of the domain is characteristic of classical logic. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 11024 | Semantics must precede proof in higher-order logics, since they are incomplete [Read] |
| Full Idea: For the realist, study of semantic structures comes before study of proofs. In higher-order logic is has to, for the logics are incomplete. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.9) | |
| A reaction: This seems to be an important general observation about any incomplete system, such as Peano arithmetic. You may dream the old rationalist dream of starting from the beginning and proving everything, but you can't. Start with truth and meaning. |
| 10985 | We should exclude second-order logic, precisely because it captures arithmetic [Read] |
| Full Idea: Those who believe mathematics goes beyond logic use that fact to argue that classical logic is right to exclude second-order logic. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 10970 | A theory of logical consequence is a conceptual analysis, and a set of validity techniques [Read] |
| Full Idea: A theory of logical consequence, while requiring a conceptual analysis of consequence, also searches for a set of techniques to determine the validity of particular arguments. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 10984 | Logical consequence isn't just a matter of form; it depends on connections like round-square [Read] |
| Full Idea: If classical logic insists that logical consequence is just a matter of the form, we fail to include as valid consequences those inferences whose correctness depends on the connections between non-logical terms (such as 'round' and 'square'). | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: He suggests that an inference such as 'round, so not square' should be labelled as 'materially valid'. |
| 10973 | A theory is logically closed, which means infinite premisses [Read] |
| Full Idea: A 'theory' is any logically closed set of propositions, ..and since any proposition has infinitely many consequences, including all the logical truths, so that theories have infinitely many premisses. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: Read is introducing this as the essential preliminary to an account of the Compactness Theorem, which relates these infinite premisses to the finite. |
| 16216 | Part of the sense of a proper name is a criterion of the thing's identity [Hawley] |
| Full Idea: A Fregean dictum is that part of the sense of proper name is a criterion of identity for the thing in question. | |
| From: Katherine Hawley (How Things Persist [2001], 3.8) | |
| A reaction: [She quotes Dummett 1981:545] We are asked to choose between this and the Kripke rigid/dubbing/causal account, with effectively no content. |
| 11007 | Quantifiers are second-order predicates [Read] |
| Full Idea: Quantifiers are second-order predicates. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.5) | |
| A reaction: [He calls this 'Frege's insight'] They seem to be second-order in Tarski's sense, that they are part of a metalanguage about the sentence, rather than being a part of the sentence. |
| 10978 | In second-order logic the higher-order variables range over all the properties of the objects [Read] |
| Full Idea: The defining factor of second-order logic is that, while the domain of its individual variables may be arbitrary, the range of the first-order variables is all the properties of the objects in its domain (or, thinking extensionally, of the sets objects). | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: The key point is that the domain is 'all' of the properties. How many properties does an object have. You need to decide whether you believe in sparse or abundant properties (I vote for very sparse indeed). |
| 10971 | A logical truth is the conclusion of a valid inference with no premisses [Read] |
| Full Idea: Logical truth is a degenerate, or extreme, case of consequence. A logical truth is the conclusion of a valid inference with no premisses, or a proposition in the premisses of an argument which is unnecessary or may be suppressed. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 10988 | Any first-order theory of sets is inadequate [Read] |
| Full Idea: Any first-order theory of sets is inadequate because of the Löwenheim-Skolem-Tarski property, and the consequent Skolem paradox. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: The limitation is in giving an account of infinities. |
| 10974 | Compactness is when any consequence of infinite propositions is the consequence of a finite subset [Read] |
| Full Idea: Classical logical consequence is compact, which means that any consequence of an infinite set of propositions (such as a theory) is a consequence of some finite subset of them. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 10975 | Compactness does not deny that an inference can have infinitely many premisses [Read] |
| Full Idea: Compactness does not deny that an inference can have infinitely many premisses. It can; but classically, it is valid if and only if the conclusion follows from a finite subset of them. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 10977 | Compactness blocks the proof of 'for every n, A(n)' (as the proof would be infinite) [Read] |
| Full Idea: Compact consequence undergenerates - there are intuitively valid consequences which it marks as invalid, such as the ω-rule, that if A holds of the natural numbers, then 'for every n, A(n)', but the proof of that would be infinite, for each number. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 10976 | Compactness makes consequence manageable, but restricts expressive power [Read] |
| Full Idea: Compactness is a virtue - it makes the consequence relation more manageable; but it is also a limitation - it limits the expressive power of the logic. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: The major limitation is that wholly infinite proofs are not permitted, as in Idea 10977. |
| 11014 | Self-reference paradoxes seem to arise only when falsity is involved [Read] |
| Full Idea: It cannot be self-reference alone that is at fault. Rather, what seems to cause the problems in the paradoxes is the combination of self-reference with falsity. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.6) |
| 11025 | Infinite cuts and successors seems to suggest an actual infinity there waiting for us [Read] |
| Full Idea: Every potential infinity seems to suggest an actual infinity - e.g. generating successors suggests they are really all there already; cutting the line suggests that the point where the cut is made is already in place. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.8) | |
| A reaction: Finding a new gambit in chess suggests it was there waiting for us, but we obviously invented chess. Daft. |
| 10979 | Although second-order arithmetic is incomplete, it can fully model normal arithmetic [Read] |
| Full Idea: Second-order arithmetic is categorical - indeed, there is a single formula of second-order logic whose only model is the standard model ω, consisting of just the natural numbers, with all of arithmetic following. It is nevertheless incomplete. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: This is the main reason why second-order logic has a big fan club, despite the logic being incomplete (as well as the arithmetic). |
| 10980 | Second-order arithmetic covers all properties, ensuring categoricity [Read] |
| Full Idea: Second-order arithmetic can rule out the non-standard models (with non-standard numbers). Its induction axiom crucially refers to 'any' property, which gives the needed categoricity for the models. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) |
| 10997 | Von Neumann numbers are helpful, but don't correctly describe numbers [Read] |
| Full Idea: The Von Neumann numbers have a structural isomorphism to the natural numbers - each number is the set of all its predecessors, so 2 is the set of 0 and 1. This helps proofs, but is unacceptable. 2 is not a set with two members, or a member of 3. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.4) |
| 16211 | A homogeneous rotating disc should be undetectable according to Humean supervenience [Hawley] |
| Full Idea: Imagine a perfectly homogeneous non-atomistic disc. A record of all the non-relational information about the world at that moment will not reveal whether the disc is rotating about a vertical axis through. This tells against Humean supervenience. | |
| From: Katherine Hawley (How Things Persist [2001], 3.2) | |
| A reaction: [Armstrong 1980 originated this, and it is famously discussed by Kripke in lectures] There will, of course, be dispositions present because of the rotation, but Lewis excludes any such modal truths. |
| 16219 | Non-linguistic things cannot be indeterminate, because they don't have truth-values at all [Hawley] |
| Full Idea: Non-linguistic objects, properties, and states of affairs cannot be indeterminate because they cannot have determinate truth-values either. No cloud is indeterminate, just as no cloud is either determinately true or determinately false. | |
| From: Katherine Hawley (How Things Persist [2001], 4.1) | |
| A reaction: If vagueness must be linguistic, this means animals can never experience it, which I doubt. Presumably 'this is a cloud' is only made vague by the vagueness of the object, rather than by the vagueness of the sentence? |
| 16223 | Maybe for the world to be vague, it must be vague in its foundations? [Hawley] |
| Full Idea: There is a question of whether there must be 'vagueness all the way down' for the world to be vague. One view is that if there is a base level of precisely describably facts, upon which all the others supervene, then the world is not really vague. | |
| From: Katherine Hawley (How Things Persist [2001], 4.5) | |
| A reaction: My understanding of the physics is that it is non-vague all the way down, and then you get to the base level which is hopelessly vague! |
| 16226 | Epistemic vagueness seems right in the case of persons [Hawley] |
| Full Idea: The epistemic account of vagueness is particularly attractive where persons are concerned. | |
| From: Katherine Hawley (How Things Persist [2001], 4.14) | |
| A reaction: You'll have to see her text for details. Interesting that there might be different views of what vagueness is for different cases. Or putting it another way, absolutely everything (said, thought, existing or done) might be vague in some way! |
| 11016 | Would a language without vagueness be usable at all? [Read] |
| Full Idea: We must ask whether a language without vagueness would be usable at all. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.7) | |
| A reaction: Popper makes a similar remark somewhere, with which I heartily agreed. This is the idea of 'spreading the word' over the world, which seems the right way of understanding it. |
| 11019 | Supervaluations say there is a cut-off somewhere, but at no particular place [Read] |
| Full Idea: The supervaluation approach to vagueness is to construe vague predicates not as ones with fuzzy borderlines and no cut-off, but as having a cut-off somewhere, but in no particular place. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.7) | |
| A reaction: Presumably you narrow down the gap by supervaluation, then split the difference to get a definite value. |
| 11012 | A 'supervaluation' gives a proposition consistent truth-value for classical assignments [Read] |
| Full Idea: A 'supervaluation' says a proposition is true if it is true in all classical extensions of the original partial valuation. Thus 'A or not-A' has no valuation for an empty name, but if 'extended' to make A true or not-true, not-A always has opposite value. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.5) |
| 16208 | Supervaluation refers to one vaguely specified thing, through satisfaction by everything in some range [Hawley] |
| Full Idea: Supervaluationists take a present-tense predication as concerning a single, but vaguely specified, moment. …It is indeterminate which of a range of moments enters into the truth conditions, but it is true if satisfied by every member of the range. | |
| From: Katherine Hawley (How Things Persist [2001], 2.7) | |
| A reaction: She is discussing stage theory, but this is a helpful clarification of the idea of supervaluation. Something can be satisfied by a whole bunch of values, even though you are not sure which one. |
| 16221 | Supervaluationism takes what the truth-value would have been if indecision was resolved [Hawley] |
| Full Idea: A supervaluationist approach involves consideration of what the truth value of the utterance would have been if semantic indecision had been resolved in this way or that. | |
| From: Katherine Hawley (How Things Persist [2001], 4.1) | |
| A reaction: At last, a lovely account of supervaluation in plain English that anyone can understand! Why don't they all do that? Well, done Katherine Hawley! ['semantic indecision' is uncertainty about what your words mean!] |
| 11013 | Identities and the Indiscernibility of Identicals don't work with supervaluations [Read] |
| Full Idea: In supervaluations, the Law of Identity has no value for empty names, and remains so if extended. The Indiscernibility of Identicals also fails if extending it for non-denoting terms, where Fa comes out true and Fb false. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.5) |
| 14502 | Plato's idea of 'structure' tends to be mathematically expressed [Plato, by Koslicki] |
| Full Idea: 'Structure' tends to be characterized by Plato as something that is mathematically expressed. | |
| From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects V.3 iv | |
| A reaction: [Koslicki is drawing on Verity Harte here] |
| 16230 | Maybe the only properties are basic ones like charge, mass and spin [Hawley] |
| Full Idea: Some philosophers suspect that properties are few and far between, that there are only properties like charge, mass, spin, and so on. | |
| From: Katherine Hawley (How Things Persist [2001], 5.1) | |
| A reaction: I think properties are very sparse, and mainly consist of physical powers, but I am not sure what I think of this. It may be 'mere semantics'. Complex properties still seem to be properties. Powers combine to make properties, I suggest. |
| 3039 | When Diogenes said he could only see objects but not their forms, Plato said it was because he had eyes but no intellect [Plato, by Diog. Laertius] |
| Full Idea: When Diogenes told Plato he saw tables and cups, but not 'tableness' and 'cupness', Plato replied that this was because Diogenes had eyes but no intellect. | |
| From: report of Plato (works [c.375 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 06.2.6 |
| 20906 | Platonists argue for the indivisible triangle-in-itself [Plato, by Aristotle] |
| Full Idea: The Platonists, on the basis of purely logical arguments, posit the existence of an indivisible 'triangle in itself'. | |
| From: report of Plato (works [c.375 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 316a15 | |
| A reaction: A helpful confirmation that geometrical figures really are among the Forms (bearing in mind that numbers are not, because they contain one another). What shape is the Form of the triangle? |
| 17948 | Plato's Forms meant that the sophists only taught the appearance of wisdom and virtue [Plato, by Nehamas] |
| Full Idea: Plato's theory of Forms allowed him to claim that the sophists and other opponents were trapped in the world of appearance. What they therefore taught was only apparent wisdom and virtue. | |
| From: report of Plato (works [c.375 BCE]) by Alexander Nehamas - Eristic,Antilogic,Sophistic,Dialectic p.118 |
| 556 | If there is one Form for both the Form and its participants, they must have something in common [Aristotle on Plato] |
| Full Idea: If there is the same Form for the Forms and for their participants, then they must have something in common. | |
| From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 991a |
| 563 | If gods are like men, they are just eternal men; similarly, Forms must differ from particulars [Aristotle on Plato] |
| Full Idea: We say there is the form of man, horse and health, but nothing else, making the same mistake as those who say that there are gods but that they are in the form of men. They just posit eternal men, and here we are not positing forms but eternal sensibles. | |
| From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 997b |
| 557 | A Form is a cause of things only in the way that white mixed with white is a cause [Aristotle on Plato] |
| Full Idea: A Form is a cause of things only in the way that white mixed with white is a cause. | |
| From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 991a |
| 565 | The Forms cannot be changeless if they are in changing things [Aristotle on Plato] |
| Full Idea: The Forms could not be changeless if they were in changing things. | |
| From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 998a |
| 16232 | An object is 'natural' if its stages are linked by certain non-supervenient relations [Hawley] |
| Full Idea: I suggest that our distinction between natural and unnatural (gerrymandered) objects corresponds to a distinction between series of stages which are and are not linked by certain non-supervenient relations. | |
| From: Katherine Hawley (How Things Persist [2001], 5.5) | |
| A reaction: See Idea 16213 for the nature of these 'relations'. I don't understand how an abstraction (as I take it) like a relation can unify a physical object. A trout-turkey is unified by a relation of some sort. Hawley defends Stage Theory. |
| 9607 | The greatest discovery in human thought is Plato's discovery of abstract objects [Brown,JR on Plato] |
| Full Idea: The greatest discovery in the history of human thought is Plato's discovery of abstract objects. | |
| From: comment on Plato (works [c.375 BCE]) by James Robert Brown - Philosophy of Mathematics Ch. 2 | |
| A reaction: Compare Idea 2860! Given the diametrically opposed views, it is clearly likely that Plato's central view is the most important idea in the history of human thought, even if it is wrong. |
| 13263 | We can grasp whole things in science, because they have a mathematics and a teleology [Plato, by Koslicki] |
| Full Idea: Due to the mathematical nature of structure and the teleological cause underlying the creation of Platonic wholes, these wholes are intelligible, and are in fact the proper objects of science. | |
| From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.3 | |
| A reaction: I like this idea, because it pays attention to the connection between how we conceive objects to be, and how we are able to think about objects. Only examining these two together enables us to grasp metaphysics. |
| 10995 | A haecceity is a set of individual properties, essential to each thing [Read] |
| Full Idea: The haecceitist (a neologism coined by Duns Scotus, pronounced 'hex-ee-it-ist', meaning literally 'thisness') believes that each thing has an individual essence, a set of properties which are essential to it. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.4) | |
| A reaction: This seems to be a difference of opinion over whether a haecceity is a set of essential properties, or a bare particular. The key point is that it is unique to each entity. |
| 13261 | Plato sees an object's structure as expressible in mathematics [Plato, by Koslicki] |
| Full Idea: The 'structure' of an object tends to be characterised by Plato as something that is mathematically expressible. | |
| From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.3 | |
| A reaction: This seems to be pure Pythagoreanism (see Idea 644). Plato is pursuing Pythagoras's research programme, of trying to find mathematics buried in every aspect of reality. |
| 13265 | Plato was less concerned than Aristotle with the source of unity in a complex object [Plato, by Koslicki] |
| Full Idea: Plato was less concerned than Aristotle with the project of how to account, in completely general terms, for the source of unity within a mereologically complex object. | |
| From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.5 | |
| A reaction: Plato seems to have simply asserted that some sort of harmony held things together. Aristotles puts the forms [eidos] within objects, rather than external, so he has to give a fuller account of what is going on in an object. He never managed it! |
| 593 | Plato's holds that there are three substances: Forms, mathematical entities, and perceptible bodies [Plato, by Aristotle] |
| Full Idea: Plato's doctrine was that the Forms and mathematicals are two substances and that the third substance is that of perceptible bodies. | |
| From: report of Plato (works [c.375 BCE]) by Aristotle - Metaphysics 1028b |
| 16200 | Are sortals spatially maximal - so no cat part is allowed to be a cat? [Hawley] |
| Full Idea: Many philosophers believe that sortal predicates are spatially maximal - for example, that no cat can be a proper spatial part of a cat. | |
| From: Katherine Hawley (How Things Persist [2001], 2.1) | |
| A reaction: This sounds reasonable until you cut the tail off a cat. Presumably what remains is a cat? So presumably that smaller part was always a cat? Only essentialism can make sense of this! You can't just invent rules for sortals. |
| 16237 | The modal features of statue and lump are disputed; when does it stop being that statue? [Hawley] |
| Full Idea: It is difficult to establish a consensus about the modal features of the statue and the lump. Could that statue be made of a different lump? Could that statue of Goliath have been spherical? Not a realistic statue of Goliath, but still the same statue? | |
| From: Katherine Hawley (How Things Persist [2001], 6) | |
| A reaction: The problem is with a wild wacky sculptor, who might say it is a statue of Goliath no matter what shape the lump takes. 'Goliath had a spherical character'. Sometimes we will say (pace Evans) it is 'roughly identical' to the original statue. |
| 16238 | Perdurantists can adopt counterpart theory, to explain modal differences of identical part-sums [Hawley] |
| Full Idea: Perdurance theory claims that lumps and statues differ modally whilst always being made of the same parts. A natural way to make this less mysterious is for perdurantists to adopt counterpart theory, where objects in different worlds are never identical. | |
| From: Katherine Hawley (How Things Persist [2001], 6.2) | |
| A reaction: This, of course, is exactly the system created by David Lewis. Personally I rather like counterparts, but perdurance seems a tad crazy. |
| 16220 | Vagueness is either in our knowledge, in our talk, or in reality [Hawley] |
| Full Idea: There are three main views of vagueness: the Epistemic view says we talk precisely, but don't know what we talk precisely about; the Semantic view is that it is loose talk, or semantic indecision; the Ontic view says it is part of how the world is. | |
| From: Katherine Hawley (How Things Persist [2001], 4.1) | |
| A reaction: [My summary of two paragraphs] She associates Williamson with the first view, Lewis with the second, and Van Inwagen with the third. |
| 16222 | Indeterminacy in objects and in properties are not distinct cases [Hawley] |
| Full Idea: There is no important distinction to be drawn between cases where indeterminacy is due to the object involved and cases where indeterminacy is due to the property involved. | |
| From: Katherine Hawley (How Things Persist [2001], 4.2) | |
| A reaction: You could always paraphrase the object's situation propertywise, or the property's situation objectwise. 'His baldness is indeterminate'; 'where does the mountainous terrain end?' |
| 16228 | The constitution theory is endurantism plus more than one object in a place [Hawley] |
| Full Idea: Constitution theorists are endurance theorists who believe that there can be more than one object exactly occupying a spatial region at a certain moment. | |
| From: Katherine Hawley (How Things Persist [2001], 5.1) | |
| A reaction: I increasingly think that this is a ridiculous view. The constitution of an object isn't a further object. A constitution is a necessary requirement for a physical object. Hylomorphism! Constitutions can't be separate - they must constitute something! |
| 16229 | Constitution theory needs sortal properties like 'being a sweater' to distinguish it from its thread [Hawley] |
| Full Idea: Constitution theorists need to posit sortal properties of 'being a thread' or 'being a sweater', as grounds for the differences betwween the sweater and the thread that constitutes it. | |
| From: Katherine Hawley (How Things Persist [2001], 5.1) | |
| A reaction: This is further grounds for thinking the constitution view ridiculous, because there are no such properties. 'Being a sweater' is a category, which something belongs in if it has all the properties of a sweater. The final property triggers sweaterhood. |
| 14492 | If the constitution view says thread and sweater are two things, why do we talk of one thing? [Hawley] |
| Full Idea: The constitution theorists, who claim that the sweater and the thread are different things, should offer some explanation of why we tend to say that there is just one thing there. They must simply claim that we 'do not count by identity'. | |
| From: Katherine Hawley (How Things Persist [2001], 5.8) | |
| A reaction: Her example is a sweater knitted from a single piece of thread. Presumably we could count by sortal identity, so there is one thread here, and there is one sweater here. We just can't add the two together. No ontological arithmetic. |
| 13260 | Plato says wholes are either containers, or they're atomic, or they don't exist [Plato, by Koslicki] |
| Full Idea: Plato considers a 'container' model for wholes (which are disjoint from their parts) [Parm 144e3-], and a 'nihilist' model, in which only wholes are mereological atoms, and a 'bare pluralities' view, in which wholes are not really one at all. | |
| From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.2 | |
| A reaction: [She cites Verity Harte for this analysis of Plato] The fourth, and best, seems to be that wholes are parts which fall under some unifying force or structure or principle. |
| 11237 | Only universals have essence [Plato, by Politis] |
| Full Idea: Plato argues that only universals have essence. | |
| From: report of Plato (works [c.375 BCE]) by Vassilis Politis - Aristotle and the Metaphysics 1.4 |
| 11238 | Plato and Aristotle take essence to make a thing what it is [Plato, by Politis] |
| Full Idea: Plato and Aristotle have a shared general conception of essence: the essence of a thing is what that thing is simply in virtue of itself and in virtue of being the very thing it is. It answers the question 'What is this very thing?' | |
| From: report of Plato (works [c.375 BCE]) by Vassilis Politis - Aristotle and the Metaphysics 1.4 |
| 16193 | 'Adverbialism' explains change by saying an object has-at-some-time a given property [Hawley] |
| Full Idea: Another strategy for the problem of change says that instantiation - the having of properties - is time-indexed, or relative to times, although properties themselves are not. This 'adverbialism' says that object has-at-t some property. | |
| From: Katherine Hawley (How Things Persist [2001], 1.5) | |
| A reaction: [She cites Johnson, Lowe and Haslanger for this] Promising. The question is whether the time index is attached to the object, to the property, or to the instantiation. The middle one is wrong. There aren't two properties - green-at-t1 and green-at-t2. |
| 16195 | Presentism solves the change problem: the green banana ceases, so can't 'relate' to the yellow one [Hawley] |
| Full Idea: Adopting presentism solves the problem of change, since it means that, once the banana is yellow, there just is no green banana, and the question of the relationship between yesterday's green banana and today's yellow one therefore does not arise. | |
| From: Katherine Hawley (How Things Persist [2001], 1.7) | |
| A reaction: Change remains kind of odd, but it is no longer the puzzlement of two things being the same when they are admitted to be different. There is only ever one thing. This is my preferred account, I think. I certainly hope past bananas don't exist. |
| 16202 | The problem of change arises if there must be 'identity' of a thing over time [Hawley] |
| Full Idea: It is the insistence on identity between objects wholly present at different times which gives rise to the problem of change. | |
| From: Katherine Hawley (How Things Persist [2001], 2.2) | |
| A reaction: My solution is to say things are the 'same', in a slightly loose non-transitive way, rather than formally identical, which is a concept from maths, not from reality. |
| 16192 | Endurance theory can relate properties to times, or timed instantiations to properties [Hawley] |
| Full Idea: Endurance theory might claim a banana stands (atemporally) in different relations to different times (being-green-at to Monday), ..or has different instantiation relations to different properties (instantiates-on-Monday to being green). | |
| From: Katherine Hawley (How Things Persist [2001], 1.3) | |
| A reaction: She suggests that the first approach is more plausible for endurantists. I think she is right (assuming these are the only two options). Monday awaits a banana, but yellow doesn't. |
| 16196 | Endurance is a sophisticated theory, covering properties, instantiation and time [Hawley] |
| Full Idea: Endurance theory is not just a default 'no-theory' theory, for it must incorporate a sophisticated account of properties and instantiation, and requires a certain view of time if it is even to be formulable. | |
| From: Katherine Hawley (How Things Persist [2001], 1.8) | |
| A reaction: A bit odd to claim it is a sophisticated theory when it is held (at least in our culture) by absolutely everyone apart from a few philosophers and physicists. The sophistication may come with trying to describe it using current metaphysical vocabulary. |
| 16197 | How does perdurance theory explain our concern for our own future selves? [Hawley] |
| Full Idea: A question for perdurance theory is whether it can account for the special concern we feel for our own future selves. | |
| From: Katherine Hawley (How Things Persist [2001], 1.8) | |
| A reaction: That is one of those questions that begins to look very mysterious whatever your theory. I favour endurantism, but me next year looks a very remote person for me to be concerned about, in comparison with the people around me now. |
| 16191 | Perdurance needs an atemporal perspective, to say that the object 'has' different temporal parts [Hawley] |
| Full Idea: Perdurance relies on our having an 'atemporal' perspective from which we can truly say a banana has both yellow and green parts, where this 'has' is not in the present tense. ..Perdurance theory cannot be expressed straightforwardly in the present tense. | |
| From: Katherine Hawley (How Things Persist [2001], 1.2) | |
| A reaction: This seems to require the tenseless B-series view of time. It seems to need a tenseless view of the past, but what does it have to say about the future? |
| 16199 | If an object is the sum of all of its temporal parts, its mass is staggeringly large! [Hawley] |
| Full Idea: The mass of an object is the sum of its nonoverlapping parts. Analogy would suggest that a persisting banana has, atemporally speaking, a mass that is the sum of all the masses of the 100g temporal parts, a worryingly large figure. | |
| From: Katherine Hawley (How Things Persist [2001], 2.1) | |
| A reaction: This is an objection to the Perdurance view that an object is the sum of all of its temporal parts. Their duration tends towards instantaneous, so the aggregate mass tends towards infinity. She says they should deny atemporal mass. |
| 16201 | Perdurance says things are sums of stages; Stage Theory says each stage is the thing [Hawley] |
| Full Idea: According to Perdurance Theory, it is long-lived sums of stages which are tennis balls, whereas according to Stage Theory, it is the stages themselves which are tennis balls. | |
| From: Katherine Hawley (How Things Persist [2001], 2.2) | |
| A reaction: These seem to be the two options if you are a four-dimensionalist, though Fine says you could be a weird three-dimensionalist and choose stage theory. |
| 16240 | If a life is essentially the sum of its temporal parts, it couldn't be shorter or longer than it was? [Hawley] |
| Full Idea: It seems that perdurance theory should identify Descartes with the sum of his temporal parts, but that means Descartes essentially lived for 54 years, which seems absurd, as he could have lived longer or less long than he in fact did. | |
| From: Katherine Hawley (How Things Persist [2001], 6.10) | |
| A reaction: [She credits Van Inwagen with this] I'm not clear why a counterpart of Descartes could not have a shorter or longer sum of parts, and still be Descartes. If the sum is rigidly designated, that is a problem for endurance too. |
| 16203 | Stage Theory seems to miss out the link between stages of the same object [Hawley] |
| Full Idea: The first worry for Stage Theory is that many present stages are bananas, and many stages tomorrow are bananas, but this seems to omit the important fact that some of those stages are intimately linked, that certain stages are the same banana. | |
| From: Katherine Hawley (How Things Persist [2001], 2.3) | |
| A reaction: Hawley has a theory to do with external relations, which I didn't find very persuasive. Just to say stages have a 'relation' seems too abstract. Stages of disparate things can also have 'relations', but presumably the wrong sort. |
| 16204 | Stage Theory says every stage is a distinct object, which gives too many objects [Hawley] |
| Full Idea: The second worry for Stage Theory is that there are far too many bananas in the world on this account. | |
| From: Katherine Hawley (How Things Persist [2001], 2.3) | |
| A reaction: The point is that each (instantaneous) stage is considered to be a whole banana (as opposed to one sum of all the stages of the banana, in the Perdurance view). A pretty serious problem, which she tries to deal with. |
| 16212 | An isolated stage can't be a banana (which involves suitable relations to other stages) [Hawley] |
| Full Idea: A single isolated stage could not be a banana, because in order to be a banana a stage must be suitably related to other stages with appropriate properties. | |
| From: Katherine Hawley (How Things Persist [2001], 3.4.1) | |
| A reaction: This seems at odds with the claim that each stage is the whole thing (rather than the long temporal 'worm' of perdurance theory). Isolated stages are instantaneous, so can't be anything, really. Her 'relations' seem hand-wavy to me. Connections? |
| 16213 | Stages of one thing are related by extrinsic counterfactual and causal relations [Hawley] |
| Full Idea: I claim that there are relations between the distinct stages of a persisting object which are not determined by the intrinsic properties of those stages. …The later stages depend, counterfactually and causally, upon the earlier stages. | |
| From: Katherine Hawley (How Things Persist [2001], 3.5) | |
| A reaction: This is the heart of her theory. How can there be a causal link between two stages which is not the result of intrinsic properties of the stages? This begins to sound like Malebranche's Occasionalism. |
| 16206 | Stages must be as fine-grained in length as change itself, so any change is a new stage [Hawley] |
| Full Idea: To account for change, stages and temporal parts must be as fine-grained as change: a material thing must have as many stages or parts as it is in incompatible states during its lifetime. | |
| From: Katherine Hawley (How Things Persist [2001], 2.4) | |
| A reaction: There seems to be a dilemma for stages here, of being so fat that they are divisible and change, or so thin that they barely exist. Lose-lose, I'd say. |
| 16205 | The stages of Stage Theory seem too thin to populate the world, or to be referred to [Hawley] |
| Full Idea: A third worry for Stage Theory is that the momentary stages themselves are just too thin to populate the world, and too thin to be the objects of reference. | |
| From: Katherine Hawley (How Things Persist [2001], 2.3) | |
| A reaction: Her three objections to her own theory add up to sufficient to refute it, in my view, though a large chunk of her book is spent trying to refute the objections. |
| 16225 | If two things might be identical, there can't be something true of one and false of the other [Hawley] |
| Full Idea: We can call the 'transference principle' the claim that if it is indeterminate whether two objects are identical, then nothing determinately true of one can be determinately false of the other. | |
| From: Katherine Hawley (How Things Persist [2001], 4.9) | |
| A reaction: The point is that Leibniz's Law could immediately be invoked to show there is no possibility of their identity. |
| 11001 | Equating necessity with truth in every possible world is the S5 conception of necessity [Read] |
| Full Idea: The equation of 'necessity' with 'true in every possible world' is known as the S5 conception, corresponding to the strongest of C.I.Lewis's five modal systems. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.4) | |
| A reaction: Are the worlds naturally, or metaphysically, or logically possible? |
| 10992 | The point of conditionals is to show that one will accept modus ponens [Read] |
| Full Idea: The point of conditionals is to show that one will accept modus ponens. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.3) | |
| A reaction: [He attributes this idea to Frank Jackson] This makes the point, against Grice, that the implication of conditionals is not conversational but a matter of logical convention. See Idea 21396 for a very different view. |
| 10989 | The standard view of conditionals is that they are truth-functional [Read] |
| Full Idea: The standard view of conditionals is that they are truth-functional, that is, that their truth-values are determined by the truth-values of their constituents. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.3) |
| 11017 | Some people even claim that conditionals do not express propositions [Read] |
| Full Idea: Some people even claim that conditionals do not express propositions. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.7) | |
| A reaction: See Idea 14283, where this appears to have been 'proved' by Lewis, and is not just a view held by some people. |
| 10983 | Knowledge of possible worlds is not causal, but is an ontology entailed by semantics [Read] |
| Full Idea: The modal Platonist denies that knowledge always depends on a causal relation. The reality of possible worlds is an ontological requirement, to secure the truth-values of modal propositions. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: [Reply to Idea 10982] This seems to be a case of deriving your metaphyics from your semantics, of which David Lewis seems to be guilty, and which strikes me as misguided. |
| 10982 | How can modal Platonists know the truth of a modal proposition? [Read] |
| Full Idea: If modal Platonism was true, how could we ever know the truth of a modal proposition? | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: I take this to be very important. Our knowledge of modal truths must depend on our knowledge of the actual world. The best answer seems to involve reference to the 'powers' of the actual world. A reply is in Idea 10983. |
| 10996 | Actualism is reductionist (to parts of actuality), or moderate realist (accepting real abstractions) [Read] |
| Full Idea: There are two main forms of actualism: reductionism, which seeks to construct possible worlds out of some more mundane material; and moderate realism, in which the actual concrete world is contrasted with abstract, but none the less real, possible worlds. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.4) | |
| A reaction: I am a reductionist, as I do not take abstractions to be 'real' (precisely because they have been 'abstracted' from the things that are real). I think I will call myself a 'scientific modalist' - we build worlds from possibilities, discovered by science. |
| 10981 | A possible world is a determination of the truth-values of all propositions of a domain [Read] |
| Full Idea: A possible world is a complete determination of the truth-values of all propositions over a certain domain. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.2) | |
| A reaction: Even if the domain is very small? Even if the world fitted the logic nicely, but was naturally impossible? |
| 16239 | To decide whether something is a counterpart, we need to specify a relevant sortal concept [Hawley] |
| Full Idea: When asked whether a possible object is a counterpart of something, we need to specify which sortal we are interested in. | |
| From: Katherine Hawley (How Things Persist [2001], 6.2) | |
| A reaction: The compares this to the 'respect' in which two things are similar. For example, what would count as a counterpart of the current British Prime Minister? De re or de dicto reference? |
| 11000 | If worlds are concrete, objects can't be present in more than one, and can only have counterparts [Read] |
| Full Idea: If each possible world constitutes a concrete reality, then no object can be present in more than one world - objects may have 'counterparts', but cannot be identical with them. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.4) | |
| A reaction: This explains clearly why in Lewis's modal realist scheme he needs counterparts instead of rigid designation. Sounds like a slippery slope. If you say 'Humphrey might have won the election', who are you talking about? |
| 17085 | A good explanation totally rules out the opposite explanation (so Forms are required) [Plato, by Ruben] |
| Full Idea: For Plato, an acceptable explanation is one such that there is no possibility of there being the opposite explanation at all, and he thought that only explanations in terms of the Forms, but never physical explanations, could meet this requirement. | |
| From: report of Plato (works [c.375 BCE]) by David-Hillel Ruben - Explaining Explanation Ch 2 | |
| A reaction: [Republic 436c is cited] |
| 10998 | The mind abstracts ways things might be, which are nonetheless real [Read] |
| Full Idea: Ways things might be are real, but only when abstracted from the actual way things are. They are brought out and distinguished by the mind, by abstraction, but are not dependent on mind for their existence. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.4) | |
| A reaction: To me this just flatly contradicts itself. The idea that the mind can 'bring something out' by its operations, with the result being then accepted as part of reality is nonsense on stilts. What is real is the powers that make the possibilities. |
| 16218 | On any theory of self, it is hard to explain why we should care about our future selves [Hawley] |
| Full Idea: It is rather difficult to say why one should care about one's future self, even on an endurance theory account of the self. | |
| From: Katherine Hawley (How Things Persist [2001], 3.9) | |
| A reaction: A nice passing remark, that strikes me forcibly as one of those basic mysteries of experience that philosophers can only gawp at, and have no theory to offer. |
| 1651 | Plato wanted to somehow control and purify the passions [Vlastos on Plato] |
| Full Idea: Plato put high on his agenda a project which did not figure in Socrates' programme at all: the hygienic conditioning of the passions. This cannot be an intellectual process, as argument cannot touch them. | |
| From: comment on Plato (works [c.375 BCE]) by Gregory Vlastos - Socrates: Ironist and Moral Philosopher p.88 | |
| A reaction: This is the standard traditional view of any thinker who exaggerates the importance and potential of reason in our lives. |
| 11005 | Negative existentials with compositionality make the whole sentence meaningless [Read] |
| Full Idea: A problem with compositionality is negative existential propositions. If some of the terms of the proposition are empty, and don't refer, then compositionality implies that the whole will lack meaning too. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.5) | |
| A reaction: I don't agree. I don't see why compositionality implies holism about sentence-meaning. If I say 'that circular square is a psychopath', you understand the predication, despite being puzzled by the singular term. |
| 10966 | A proposition objectifies what a sentence says, as indicative, with secure references [Read] |
| Full Idea: A proposition makes an object out of what is said or expressed by the utterance of a certain sort of sentence, namely, one in the indicative mood which makes sense and doesn't fail in its references. It can then be an object of thought and belief. | |
| From: Stephen Read (Thinking About Logic [1995], Ch.1) | |
| A reaction: Nice, but two objections: I take it to be crucial to propositions that they eliminate ambiguities, and I take it that animals are capable of forming propositions. Read seems to regard them as fictions, but I take them to be brain events. |
| 3324 | Plato's whole philosophy may be based on being duped by reification - a figure of speech [Benardete,JA on Plato] |
| Full Idea: Plato is liable to the charge of having been duped by a figure of speech, albeit the most profound of all, the trope of reification. | |
| From: comment on Plato (works [c.375 BCE]) by José A. Benardete - Metaphysics: the logical approach Ch.12 | |
| A reaction: That might be a plausible account if his view was ridiculous, but given how many powerful friends Plato has, especially in the philosophy of mathematics, we should assume he was cleverer than that. |
| 7503 | Plato never refers to examining the conscience [Plato, by Foucault] |
| Full Idea: Plato never speaks of the examination of conscience - never! | |
| From: report of Plato (works [c.375 BCE]) by Michel Foucault - On the Genealogy of Ethics p.276 | |
| A reaction: Plato does imply some sort of self-evident direct knowledge about that nature of a healthy soul. Presumably the full-blown concept of conscience is something given from outside, from God. In 'Euthyphro', Plato asserts the primacy of morality (Idea 337). |
| 2173 | As religion and convention collapsed, Plato sought morals not just in knowledge, but in the soul [Williams,B on Plato] |
| Full Idea: Once gods and fate and social expectation were no longer there, Plato felt it necessary to discover ethics inside human nature, not just as ethical knowledge (Socrates' view), but in the structure of the soul. | |
| From: comment on Plato (works [c.375 BCE]) by Bernard Williams - Shame and Necessity II - p.43 | |
| A reaction: anti Charles Taylor |
| 9274 | Plato's legacy to European thought was the Good, the Beautiful and the True [Plato, by Gray] |
| Full Idea: Plato's legacy to European thought was a trio of capital letters - the Good, the Beautiful and the True. | |
| From: report of Plato (works [c.375 BCE]) by John Gray - Straw Dogs 2.8 | |
| A reaction: It seems to have been Baumgarten who turned this into a slogan (Idea 8117). Gray says these ideals are lethal, but I identify with them very strongly, and am quite happy to see the good life as an attempt to find the right balance between them. |
| 94 | Pleasure is better with the addition of intelligence, so pleasure is not the good [Plato, by Aristotle] |
| Full Idea: Plato says the life of pleasure is more desirable with the addition of intelligence, and if the combination is better, pleasure is not the good. | |
| From: report of Plato (works [c.375 BCE]) by Aristotle - Nicomachean Ethics 1172b27 | |
| A reaction: It is obvious why we like pleasure, but not why intelligence makes it 'better'. Maybe it is just because we enjoy intelligence? |
| 17947 | Plato decided that the virtuous and happy life was the philosophical life [Plato, by Nehamas] |
| Full Idea: Plato came to the conclusion that virtue and happiness consist in the life of philosophy itself. | |
| From: report of Plato (works [c.375 BCE]) by Alexander Nehamas - Eristic,Antilogic,Sophistic,Dialectic p.117 | |
| A reaction: This view is obviously ridiculous, because it largely excludes almost the entire human race, which sees philosophy as a cul-de-sac, even if it is good. But virtue and happiness need some serious thought. |
| 6015 | Plato, unusually, said that theoretical and practical wisdom are inseparable [Plato, by Kraut] |
| Full Idea: Two virtues that are ordinarily kept distinct - theoretical and practical wisdom - are joined by Plato; he thinks that neither one can be fully possessed unless it is combined with the other. | |
| From: report of Plato (works [c.375 BCE]) by Richard Kraut - Plato | |
| A reaction: I get the impression that this doctrine comes from Socrates, whose position is widely reported as 'intellectualist'. Aristotle certainly held the opposite view. |
| 2912 | Plato is boring [Nietzsche on Plato] |
| Full Idea: Plato is boring. | |
| From: comment on Plato (works [c.375 BCE]) by Friedrich Nietzsche - Twilight of the Idols 9.2 |
| 16215 | Causation is nothing more than the counterfactuals it grounds? [Hawley] |
| Full Idea: Counterfactual accounts of causation say that a causal connection is exhausted by the counterfactuals it appears to ground. | |
| From: Katherine Hawley (How Things Persist [2001], 3.5) | |
| A reaction: I am bewildered as to how this became a respectable view in philosophy. I quite understand that this might exhaust the 'logic' of causal relations. Presumably you can have counterfactuals in mathematics which are not causal? |
| 1526 | Almost everyone except Plato thinks that time could not have been generated [Plato, by Aristotle] |
| Full Idea: With a single exception (Plato) everyone agrees about time - that it is not generated. Democritus says time is an obvious example of something not generated. | |
| From: report of Plato (works [c.375 BCE]) by Aristotle - Physics 251b14 |
| 16207 | Time could be discrete (like integers) or dense (rationals) or continuous (reals) [Hawley] |
| Full Idea: There seem to be three possible ways for time to be fine-grained. The ordering of instants could be discrete (like the integers), dense (like the rational numbers) or continuous (like the real numbers). | |
| From: Katherine Hawley (How Things Persist [2001], 2.5) | |
| A reaction: She seems to assume that time must be 'grained', but I would take the continuous view to imply that there is no grain at all (which is bad news for her version of stage theory). |