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All the ideas for 'Natural Kinds', 'The Metaphysics of Modality' and 'Guidebook to Wittgenstein's Tractatus'

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51 ideas

1. Philosophy / E. Nature of Metaphysics / 2. Possibility of Metaphysics
There must be a plausible epistemological theory alongside any metaphysical theory [Forbes,G]
     Full Idea: No metaphysical account which renders it impossible to give a plausible epistemological theory is to be countenanced.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 9.1)
     A reaction: It is hard to object to this principle, though we certainly don't want to go verificationist, and thus rule out speculations about metaphysics which are beyond any possible knowledge. Some have tried to prove that something must exist (e.g. Jacquette).
1. Philosophy / G. Scientific Philosophy / 3. Scientism
Philosophy is continuous with science, and has no external vantage point [Quine]
     Full Idea: I see philosophy not as an a priori propaedeutic or groundwork for science, but as continuous with science. I see philosophy and science as in the same boat. …There is no external vantage point, no first philosophy.
     From: Willard Quine (Natural Kinds [1969], p.126)
     A reaction: Philosophy is generalisation. Science holds the upper hand, because it settles the subject-matter to be generalised.
1. Philosophy / H. Continental Philosophy / 3. Hermeneutics
Interpreting a text is representing it as making sense [Morris,M]
     Full Idea: Interpreting a text is a matter of making sense of it. And to make sense of a text is to represent it as making sense.
     From: Michael Morris (Guidebook to Wittgenstein's Tractatus [2008], Intro.2)
     A reaction: 'Making sense' is obviously not a very precise or determinate concept. It is probably better to say that the process is 'trying' to make sense of the text, because most texts don't totally make sense.
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / a. Symbols of PL
The symbol 'ι' forms definite descriptions; (ιx)F(x) says 'the x which is such that F(x)' [Forbes,G]
     Full Idea: We use the symbol 'ι' (Greek 'iota') to form definite descriptions, reading (ιx)F(x) as 'the x which is such that F(x)', or simply as 'the F'.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 4.1)
     A reaction: Compare the lambda operator in modal logic, which picks out predicates from similar formulae.
5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
Bipolarity adds to Bivalence the capacity for both truth values [Morris,M]
     Full Idea: According to the Principle of Bipolarity, every meaningful sentence must be capable both of being true and of being false. It is not enough merely that every sentence must be either true or false (which is Bivalence).
     From: Michael Morris (Guidebook to Wittgenstein's Tractatus [2008], 3D)
     A reaction: It is said that early Wittgenstein endorses this. That is, in addition to being true, the sentence must be capable of falsehood (and vice versa). This seems to be flirting with the verification principle. I presume it is 'affirmative' sentences.
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / d. and
Is the meaning of 'and' given by its truth table, or by its introduction and elimination rules? [Forbes,G]
     Full Idea: The typical semantic account of validity for propositional connectives like 'and' presupposes that meaning is given by truth-tables. On the natural deduction view, the meaning of 'and' is given by its introduction and elimination rules.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 4.4)
5. Theory of Logic / G. Quantification / 1. Quantification
Conjunctive and disjunctive quantifiers are too specific, and are confined to the finite [Morris,M]
     Full Idea: There are two problems with defining the quantifiers in terms of conjunction and disjunction. The general statements are unspecific, and do not say which things have the properties, and also they can't range over infinite objects.
     From: Michael Morris (Guidebook to Wittgenstein's Tractatus [2008], 5C)
     A reaction: That is, the universal quantifier is lots of ands, and the existential is lots of ors. If there only existed finite objects, then naming them all would be universal, and the infinite wouldn't be needed.
6. Mathematics / A. Nature of Mathematics / 2. Geometry
Klein summarised geometry as grouped together by transformations [Quine]
     Full Idea: Felix Klein's so-called 'Erlangerprogramm' in geometry involved characterizing the various branches of geometry by what transformations were irrelevant to each.
     From: Willard Quine (Natural Kinds [1969], p.137)
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / c. Counting procedure
Counting needs to distinguish things, and also needs the concept of a successor in a series [Morris,M]
     Full Idea: Just distinguishing things is not enough for counting (and hence arithmetic). We need the crucial extra notion of the successor in a series of some kind.
     From: Michael Morris (Guidebook to Wittgenstein's Tractatus [2008], Intro.5)
     A reaction: This is a step towards the Peano Axioms of arithmetic. The successors could be fingers and toes, taken in a conventional order, and matched one-to-one to the objects. 'My right big toe of cows' means 16 cows (but non-verbally).
To count, we must distinguish things, and have a series with successors in it [Morris,M]
     Full Idea: Distinguishing between things is not enough for counting. …We need the crucial extra notion of a successor in a series of a certain kind.
     From: Michael Morris (Guidebook to Wittgenstein's Tractatus [2008], Intro)
     A reaction: This is the thinking that led to the Dedekind-Peano axioms for arithmetic. E.g. each series member can only have one successor. There is an unformalisable assumption that the series can then be applied to the things.
Discriminating things for counting implies concepts of identity and distinctness [Morris,M]
     Full Idea: The discrimination of things for counting needs to bring with it the notion of identity (and, correlatively, distinctness).
     From: Michael Morris (Guidebook to Wittgenstein's Tractatus [2008], Intro.5)
     A reaction: Morris is exploring how practices like counting might reveal necessary truths about the world.
7. Existence / C. Structure of Existence / 8. Stuff / a. Pure stuff
Mass terms just concern spread, but other terms involve both spread and individuation [Quine]
     Full Idea: 'Yellow' and 'water' are mass terms, concerned only with spread; 'apple' and 'square' are terms of divided reference, concerned with both spread and individuation.
     From: Willard Quine (Natural Kinds [1969], p.124)
     A reaction: Would you like some apple? Pass me that water. It is helpful to see that it is a requirement of 'individuation' that is missing from terms for stuff.
7. Existence / D. Theories of Reality / 10. Vagueness / d. Vagueness as linguistic
Vagueness problems arise from applying sharp semantics to vague languages [Forbes,G]
     Full Idea: It is very plausible that the sorites paradoxes arose from the application of a semantic apparatus appropriate only for sharp predicates to languages containing vague predicates (rather than from deficiency of meaning, or from incoherence).
     From: Graeme Forbes (The Metaphysics of Modality [1985], 7.3)
     A reaction: Sounds wrong. Of course, logic has been designed for sharp predicates, and natural languages are awash with vagueness. But the problems of vagueness bothered lawyers long before logicians like Russell began to worry about it.
8. Modes of Existence / C. Powers and Dispositions / 6. Dispositions / a. Dispositions
Once we know the mechanism of a disposition, we can eliminate 'similarity' [Quine]
     Full Idea: Once we can legitimize a disposition term by defining the relevant similarity standard, we are apt to know the mechanism of the disposition, and so by-pass the similarity.
     From: Willard Quine (Natural Kinds [1969], p.135)
     A reaction: I love mechanisms, but can we characterise mechanisms without mentioning powers and dispositions? Quine's dream is to eliminate 'similarity'.
8. Modes of Existence / C. Powers and Dispositions / 6. Dispositions / d. Dispositions as occurrent
We judge things to be soluble if they are the same kind as, or similar to, things that do dissolve [Quine]
     Full Idea: Intuitively, what qualifies a thing as soluble though it never gets into water is that it is of the same kind as the things that actually did or will dissolve; it is similar to them.
     From: Willard Quine (Natural Kinds [1969], p.130)
     A reaction: If you can judge that the similar things 'will' dissolve, you can cut to the chase and judge that this thing will dissolve.
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
In all instances of identity, there must be some facts to ensure the identity [Forbes,G]
     Full Idea: For each instance of identity or failure of identity, there must be facts in virtue of which that instance obtains. ..Enough has been said to lend this doctrine some plausibility.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 5.5)
     A reaction: Penelope Mackie picks this out from Forbes as a key principle. It sounds to be in danger of circularity, unless the 'facts' can be cited without referring to, or implicitly making use of, identities - which seems unlikely.
9. Objects / B. Unity of Objects / 3. Unity Problems / d. Coincident objects
If we combined two clocks, it seems that two clocks may have become one clock. [Forbes,G]
     Full Idea: If we imagine a possible world in which two clocks in a room make one clock from half the parts of each, the judgement 'these two actual clocks could have been a single clock' does not seem wholly false.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 7.4)
     A reaction: You would, of course, have sufficient parts left over to make a second clock, so they look like a destroyed clock, so I don't think I find Forbes's intuition on this one very persuasive.
9. Objects / D. Essence of Objects / 3. Individual Essences
Only individual essences will ground identities across worlds in other properties [Forbes,G, by Mackie,P]
     Full Idea: Forbes argues that, unless we posit individual essences, we cannot guarantee that identities across possible worlds will be appropriately grounded in other properties.
     From: report of Graeme Forbes (The Metaphysics of Modality [1985]) by Penelope Mackie - How Things Might Have Been 2.4
     A reaction: There is a confrontation between Wiggins, who says identity is primitive, and Forbes, who says identity must be grounded in other properties. I think I side with Forbes.
An individual essence is a set of essential properties which only that object can have [Forbes,G]
     Full Idea: An individual essence of an object x is a set of properties I which satisfies the following conditions: i. every property P in I is an essential property of x; ii. it is not possible that some object y distinct from x has every member of I.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 5.1)
     A reaction: I am coming to the view that stable natural kinds (like electrons or gold) do not have individual essences, but complex kinds (like tigers or tables) do. The view is based on the idea that explanatory power is what individuates an essence.
Non-trivial individual essence is properties other than de dicto, or universal, or relational [Forbes,G]
     Full Idea: A non-trivial individual essence is properties other than a) those following from a de dicto truth, b) properties of existence and self-identity (or their cognates), c) properties derived from necessities in some other category.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 5.1)
     A reaction: [I have compressed Forbes] Rather than adding all these qualificational clauses to our concept, we could just tighten up on the notion of a property, saying it is something which is causally efficacious, and hence explanatory.
9. Objects / D. Essence of Objects / 5. Essence as Kind
Essential properties depend on a category, and perhaps also on particular facts [Forbes,G]
     Full Idea: The essential properties of a thing will typically depend upon what category of thing it is, and perhaps also on some more particular facts about the thing itself.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 5.1)
     A reaction: I see no way of dispensing with the second requirement, in the cases of complex entities like animals. If all samples are the same, then of course we can define a sample's essence through its kind, but not if samples differ in any way.
9. Objects / D. Essence of Objects / 7. Essence and Necessity / a. Essence as necessary properties
Essential properties are those without which an object could not exist [Forbes,G]
     Full Idea: An essential property of an object x is a property without possessing which x could not exist.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 5.1)
     A reaction: This is certainly open to question. See Joan Kung's account of Aristotle on essence. I am necessarily more than eight years old (now), and couldn't exist without that property, but is the property part of my essence?
9. Objects / D. Essence of Objects / 11. Essence of Artefacts
Same parts does not ensure same artefact, if those parts could constitute a different artefact [Forbes,G]
     Full Idea: Sameness of parts is not sufficient for identity of artefacts at a world, since the very same parts may turn up at different times as the parts of artefacts with different designs and functions.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 7.2)
     A reaction: Thus the Ship of Theseus could be dismantled and turned into a barn (as happened with the 'Mayflower'). They could then be reconstituted as the ship, which would then have two beginnings (as Chris Hughes has pointed out).
Artefacts have fuzzy essences [Forbes,G]
     Full Idea: Artefacts can be ascribed fuzzy essences. ...We might say that it is essential to an artefact to have 'most' of its parts.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 7.6)
     A reaction: I think I prefer to accept the idea that essences are unstable things, in all cases. For all we know, electrons might subtly change their general character, or cease to be uniform, tomorrow. Essences explain, and what needs explaining changes.
9. Objects / E. Objects over Time / 12. Origin as Essential
An individual might change their sex in a world, but couldn't have differed in sex at origin [Forbes,G]
     Full Idea: In the time of a single world, the same individual can undergo a change of sex, but it is less clear that an individual of one sex could have been, from the outset, an individual of another.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 6.5)
     A reaction: I don't find this support for essentiality of origin very persuasive. I struggle with these ideas. Given my sex yesterday, then presumably I couldn't have had a different sex yesterday. Given that pigs can fly, pigs can fly. What am I missing?
9. Objects / F. Identity among Objects / 1. Concept of Identity
Identities must hold because of other facts, which must be instrinsic [Forbes,G, by Mackie,P]
     Full Idea: Forbes has two principles of identity, which we can call the No Bare Identities Principle (identities hold in virtue of other facts), and the No Extrinsic Determination Principle (that only intrinsic facts of a thing establish identity).
     From: report of Graeme Forbes (The Metaphysics of Modality [1985], 127-8) by Penelope Mackie - How Things Might Have Been 2.7
     A reaction: The job of the philosopher is to prise apart the real identities of things from the way in which we conceive of identities. I take these principles to apply to real identities, not conceptual identities.
10. Modality / A. Necessity / 4. De re / De dicto modality
De re modal formulae, unlike de dicto, are sensitive to transworld identities [Forbes,G]
     Full Idea: The difference between de re and de dicto formulae is a difference between formulae which are, and formulae which are not, sensitive to the identities of objects at various worlds.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 3.1)
10. Modality / C. Sources of Modality / 4. Necessity from Concepts
De re necessity is a form of conceptual necessity, just as de dicto necessity is [Forbes,G]
     Full Idea: De re necessity does not differ from de dicto necessity in respect of how it arises: it is still a form of conceptual necessity.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 9.4)
     A reaction: [Forbes proceeds to argue for this claim] Forbes defends a form of essentialism, but takes the necessity to arise from a posteriori truths because of the a priori involvement of other concepts (rather as Kripke argues).
10. Modality / E. Possible worlds / 1. Possible Worlds / c. Possible worlds realism
Unlike places and times, we cannot separate possible worlds from what is true at them [Forbes,G]
     Full Idea: There is no means by which we might distinguish a possible world from what is true at it. ...Whereas our ability to separate a place, or a time, from its occupier is crucial to realism about places and times, as is a distance relation.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 4.2)
     A reaction: He is objecting to Lewis's modal realism. I'm not fully convinced. It depends whether we are discussing real ontology or conceptual space. In the latter I see no difference between times and possible worlds. In ontology, a 'time' is weird.
The problem with possible worlds realism is epistemological; we can't know properties of possible objects [Forbes,G]
     Full Idea: The main objection to realism about worlds is from epistemology. Knowledge of properties of objects requires experience of these objects, which must be within the range of our sensory faculties, but only concrete actual objects achieve that.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 4.2)
     A reaction: This pinpoints my dislike of the whole possible worlds framework, ontologically speaking. I seem to be an actualist. I take possibilities to be inferences to the best explanation from the powers we know of in the actual world. We experience potentiality.
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / a. Nature of possible worlds
Possible worlds are points of logical space, rather like other times than our own [Forbes,G]
     Full Idea: Someone impressed by the parallel between tense and modal operators ...might suggest that just as we can speak of places and times forming their own manifolds or spaces, so we can say that worlds are the points of logical space.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 4.2)
     A reaction: I particularly like the notion of worlds being "points of logical space", and am inclined to remove it from this context and embrace it as the correct way to understand possible worlds. We must understand logical or conceptual space.
10. Modality / E. Possible worlds / 3. Transworld Objects / a. Transworld identity
Transworld identity concerns the limits of possibility for ordinary things [Forbes,G]
     Full Idea: An elucidation of transworld identity can be regarded as an elucidation of the boundaries of possibility for ordinary things.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 5.1)
     A reaction: I presume that if we don't search for some such criterion, we just have to face the possibility that Aristotle could have been a poached egg in some possible world. To know the bounds of possibility, study the powers of actual objects.
The problem of transworld identity can be solved by individual essences [Forbes,G]
     Full Idea: The motivation for investigating individual essences should be obvious, since if every object has such an essence, the problem of elucidating transworld identity can be solved.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 5.1)
     A reaction: It is important that, if necessary, the identities be 'individual', and not just generic, by sortal, or natural kind. We want to reason about (and explain) truths at the fine-grained level of the individual, not just at the broad level of generalisation.
10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
Counterpart theory is not good at handling the logic of identity [Forbes,G]
     Full Idea: The outstanding technical objection to counterpart-theoretic semantics concerns its handling of the logic of identity. In quantified S5 (the orthodox semantics) a = b → □(a = b) is valid, but 'a' must not attach to two objects.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 3.5)
10. Modality / E. Possible worlds / 3. Transworld Objects / d. Haecceitism
Haecceitism attributes to each individual a primitive identity or thisness [Forbes,G]
     Full Idea: Haecceitism attributes to each individual a primitive identity or thisness, as opposed to the sort of essentialism that gives non-trivial conditions sufficient for transworld identity.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 6.6)
     A reaction: 'Haecceitism' is the doctrine that things have primitive identity. A 'haecceity' is a postulated property which actually does the job. The key point of the view is that whatever it is is 'primitive', and not complex, or analysable. I don't believe it.
We believe in thisnesses, because we reject bizarre possibilities as not being about that individual [Forbes,G]
     Full Idea: The natural response to an unreasonable hypothesis of possibility for an object x, that in such a state of affairs it would not be x which satisfies the conditions, is evidence that we do possess concepts of thisness for individuals.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 9.4)
     A reaction: We may have a 'concept' of thisness, but we needn't be committed to the 'existence' of a thisness. There is a fairly universal intuition that cessation of existence of an entity when it starts to change can be a very vague matter.
14. Science / A. Basis of Science / 3. Experiment
Science is common sense, with a sophisticated method [Quine]
     Full Idea: Sciences differ from common sense only in the degree of methodological sophistication.
     From: Willard Quine (Natural Kinds [1969], p.129)
     A reaction: Science is normal thinking about the world, but it is teamwork, with the bar set very high.
14. Science / C. Induction / 1. Induction
Induction is just more of the same: animal expectations [Quine]
     Full Idea: Induction is essentially only more of the same: animal expectation or habit formation.
     From: Willard Quine (Natural Kinds [1969], p.125)
     A reaction: My working definition of induction is 'learning from experience', but that doesn't disagree with Quine. Lipton has a richer account of different types of induction. Quine's point is that it rests on resemblance.
Induction relies on similar effects following from each cause [Quine]
     Full Idea: Induction expresses our hopes that similar causes will have similar effects.
     From: Willard Quine (Natural Kinds [1969], p.125)
     A reaction: Some top philosophers are also top teachers, and Quine was one of them, in his writings. He boils it down for the layman. Once again, he is pointing to the fundamental role of the similarity relation.
14. Science / C. Induction / 5. Paradoxes of Induction / a. Grue problem
Grue is a puzzle because the notions of similarity and kind are dubious in science [Quine]
     Full Idea: What makes Goodman's example a puzzle is the dubious scientific standing of a general notion of similarity, or of kind.
     From: Willard Quine (Natural Kinds [1969], p.116)
     A reaction: Illuminating. It might be best expressed as revealing a problem with sortal terms, as employed by Geach, or by Wiggins. Grue is a bit silly, but sortals are subject to convention and culture. 'Natural' properties seem needed.
15. Nature of Minds / C. Capacities of Minds / 7. Seeing Resemblance
General terms depend on similarities among things [Quine]
     Full Idea: The usual general term, whether a common noun or a verb or an adjective, owes its generality to some resemblance among the things referred to.
     From: Willard Quine (Natural Kinds [1969], p.116)
     A reaction: Quine has a nice analysis of the basic role of similarity in a huge amount of supposedly strict scientific thought.
To learn yellow by observation, must we be told to look at the colour? [Quine]
     Full Idea: According to the 'respects' view, our learning of yellow by ostension would have depended on our first having been told or somehow apprised that it was going to be a question of color.
     From: Willard Quine (Natural Kinds [1969], p.122)
     A reaction: Quine suggests there is just one notion of similarity, and respects can be 'abstracted' afterwards. Even the ontologically ruthless Quine admits psychological abstraction!
Standards of similarity are innate, and the spacing of qualities such as colours can be mapped [Quine]
     Full Idea: A standard of similarity is in some sense innate. The spacing of qualities (such as red, pink and blue) can be explored and mapped in the laboratory by experiments. They are needed for all learning.
     From: Willard Quine (Natural Kinds [1969], p.123)
     A reaction: This reasserts Hume's original point in more scientific terms. It is one of the undeniable facts about our perceptions of qualities and properties, no matter how platonist your view of universals may be.
Similarity is just interchangeability in the cosmic machine [Quine]
     Full Idea: Things are similar to the extent that they are interchangeable parts of the cosmic machine.
     From: Willard Quine (Natural Kinds [1969], p.134)
     A reaction: This is a major idea for Quine, because it is a means to gradually eliminate the fuzzy ideas of 'resemblance' or 'similarity' or 'natural kind' from science. I love it! Two tigers are same insofar as they are substitutable.
19. Language / C. Assigning Meanings / 3. Predicates
Projectible predicates can be universalised about the kind to which they refer [Quine]
     Full Idea: 'Projectible' predicates are predicates F and G whose shared instances all do count, for whatever reason, towards confirmation of 'All F are G'. ….A projectible predicate is one that is true of all and only the things of a kind.
     From: Willard Quine (Natural Kinds [1969], p.115-6)
     A reaction: Both Quine and Goodman are infuriatingly brief about the introduction of this concept. 'Red' is true of all ripe tomatoes, but not 'only' of them. Hardly any predicates are true only of one kind. Is that a scholastic 'proprium'?
19. Language / D. Propositions / 1. Propositions
There must exist a general form of propositions, which are predictabe. It is: such and such is the case [Morris,M]
     Full Idea: The existence of a general propositional form is proved by the fact that there cannot be a proposition whose form could not have been foreseen (i.e. constructed). The general form of the proposition is: Such and such is the case.
     From: Michael Morris (Guidebook to Wittgenstein's Tractatus [2008], 4.5)
     A reaction: [last bit in Ogden translation] LW eventually expresses this symbolically. We could just say a proposition is an assertion. This strikes as either a rather empty claim, or an unfounded one.
26. Natural Theory / B. Natural Kinds / 1. Natural Kinds
Quine probably regrets natural kinds now being treated as essences [Quine, by Dennett]
     Full Idea: The concept of natural kinds was reintroduced by Quine, who may now regret the way it has become a stand-in for the dubious but covertly popular concept of essences.
     From: report of Willard Quine (Natural Kinds [1969]) by Daniel C. Dennett - Consciousness Explained 12.2 n2
     A reaction: He is right that Quine would regret it, and he is right that we can't assume that there are necessary essences just because there seem to be stable natural kinds, but personally I am an essentialist, so I'm not that bothered.
If similarity has no degrees, kinds cannot be contained within one another [Quine]
     Full Idea: If similarity has no degrees there is no containing of kinds within broader kinds. If colored things are a kind, they are similar, but red things are too narrow for a kind. If red things are a kind, colored things are not similar, and it's too broad.
     From: Willard Quine (Natural Kinds [1969], p.118)
     A reaction: [compressed] I'm on Quine's side with this. We glibly talk of 'kinds', but the criteria for sorting things into kinds seems to be a mess. Quine goes on to offer a better account than the (diadic, yes-no) one rejected here.
Comparative similarity allows the kind 'colored' to contain the kind 'red' [Quine]
     Full Idea: With the triadic relation of comparative similarity, kinds can contain one another, as well as overlapping. Red and colored things can both count as kinds. Colored things all resemble one another, even though less than red things do.
     From: Willard Quine (Natural Kinds [1969], p.119)
     A reaction: [compressed] Quine claims that comparative similarity is necessary for kinds - that there be some 'foil' in a similarity - that A is more like C than B is.
26. Natural Theory / B. Natural Kinds / 3. Knowing Kinds
You can't base kinds just on resemblance, because chains of resemblance are a muddle [Quine]
     Full Idea: If kinds are based on similarity, this has the Imperfect Community problem. Red round, red wooden and round wooden things all resemble one another somehow. There may be nothing outside the set resembling them, so it meets the definition of kind.
     From: Willard Quine (Natural Kinds [1969], p.120)
     A reaction: [ref. to Goodman 'Structure' 2nd 163- , which attacks Carnap on this] This suggests an invocation of Wittgenstein's family resemblance, which won't be much help for natural kinds.
26. Natural Theory / D. Laws of Nature / 4. Regularities / a. Regularity theory
It is hard to see how regularities could be explained [Quine]
     Full Idea: Why there have been regularities is an obscure question, for it is hard to see what would count as an answer.
     From: Willard Quine (Natural Kinds [1969], p.126)
     A reaction: This is the standard pessimism of the 20th century Humeans, but it strikes me as comparable to the pessimism about science found in Locke and Hume. Regularities are explained all the time by scientists, though the lowest level may be hopeless.