48 ideas
19275 | You cannot understand what exists without understanding possibility and necessity [Hale] |
Full Idea: I defend the thesis that questions about what kinds of things there are cannot be properly understood or adequately answered without recourse to considerations about possibility and necessity. | |
From: Bob Hale (Necessary Beings [2013], Intro) | |
A reaction: Good. I would say that this is a growing realisation in contemporary philosophy. The issue is focused when we ask what are the limitations of Quine's approach to metaphysics. If you don't see possibilities around you, you are a fool. |
19291 | A canonical defintion specifies the type of thing, and what distinguish this specimen [Hale] |
Full Idea: One might think of a full dress, or canonical, definition as specifying what type of thing it is, and what distinguishes it from everything else within its type. | |
From: Bob Hale (Necessary Beings [2013], 06.4) | |
A reaction: Good! At last someone embraces the Aristotelian ideas that definitions are a) quite extensive and detailed (unlike lexicography), and b) they aim to get right down to the individual. In that sense, an essence is captured by a definition. |
19301 | With a negative free logic, we can dispense with the Barcan formulae [Hale] |
Full Idea: I reject both Barcan and Converse Barcan by adopting a negative free logic. | |
From: Bob Hale (Necessary Beings [2013], 11.3) | |
A reaction: See section 9.2 of Hale's book, where he makes his case. I can't evaluate this bold move, though I don't like the Barcan Formulae. We can anticipate objections to Hale: are you prepared to embrace the unexpected consequences of your new logic? |
19297 | The two Barcan principles are easily proved in fairly basic modal logic [Hale] |
Full Idea: If the Brouwersche principle, p ⊃ □◊p is adjoined to a standard quantified vesion of the weakest modal logic K, then one can prove both the Barcan principle, and its converse. | |
From: Bob Hale (Necessary Beings [2013], 09.2) | |
A reaction: The Brouwersche principle (that p implies that p must be possible) sounds reasonable, but the Barcan principles strike me as false, so something has to give. They are theorems of S5. Hale proposes giving up classical logic. |
19296 | If second-order variables range over sets, those are just objects; properties and relations aren't sets [Hale] |
Full Idea: Contrary to what Quine supposes, it is neither necessary nor desirable to interpret bound higher-order variables as ranging over sets. Sets are a species of object. They should range over entities of a completely different type: properties and relations. | |
From: Bob Hale (Necessary Beings [2013], 08.2) | |
A reaction: This helpfully clarifies something which was confusing me. If sets are objects, then 'second-order' logic just seems to be the same as first-order logic (rather than being 'set theory in disguise'). I quantify over properties, but deny their existence! |
19289 | Maybe conventionalism applies to meaning, but not to the truth of propositions expressed [Hale] |
Full Idea: An old objection to conventionalism claims that it confuses sentences with propositions, confusing what makes sentences mean what they do with what makes them (as propositions) true. | |
From: Bob Hale (Necessary Beings [2013], 05.2) | |
A reaction: The conventions would presumably apply to the sentences, but not to the propositions. Since I think that focusing on propositions solves a lot of misunderstandings in modern philosophy, I like the sound of this. |
19298 | Unlike axiom proofs, natural deduction proofs needn't focus on logical truths and theorems [Hale] |
Full Idea: In contrast with axiomatic systems, in natural deductions systems of logic neither the premises nor the conclusions of steps in a derivation need themselves be logical truths or theorems of logic. | |
From: Bob Hale (Necessary Beings [2013], 09.2 n7) | |
A reaction: Not sure I get that. It can't be that everything in an axiomatic proof has to be a logical truth. How would you prove anything about the world that way? I'm obviously missing something. |
9901 | Numbers can't be sets if there is no agreement on which sets they are [Benacerraf] |
Full Idea: The fact that Zermelo and Von Neumann disagree on which particular sets the numbers are is fatal to the view that each number is some particular set. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], II) | |
A reaction: I agree. A brilliantly simple argument. There is the possibility that one of the two accounts is correct (I would vote for Zermelo), but it is not actually possible to prove it. |
9912 | There are no such things as numbers [Benacerraf] |
Full Idea: There are no such things as numbers. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], IIIC) | |
A reaction: Mill said precisely the same (Idea 9794). I think I agree. There has been a classic error of reification. An abstract pattern is not an object. If I coin a word for all the three-digit numbers in our system, I haven't created a new 'object'. |
9151 | Benacerraf says numbers are defined by their natural ordering [Benacerraf, by Fine,K] |
Full Idea: Benacerraf thinks of numbers as being defined by their natural ordering. | |
From: report of Paul Benacerraf (What Numbers Could Not Be [1965]) by Kit Fine - Cantorian Abstraction: Recon. and Defence §5 | |
A reaction: My intuition is that cardinality is logically prior to ordinality, since that connects better with the experienced physical world of objects. Just as the fact that people have different heights must precede them being arranged in height order. |
13891 | To understand finite cardinals, it is necessary and sufficient to understand progressions [Benacerraf, by Wright,C] |
Full Idea: Benacerraf claims that the concept of a progression is in some way the fundamental arithmetical notion, essential to understanding the idea of a finite cardinal, with a grasp of progressions sufficing for grasping finite cardinals. | |
From: report of Paul Benacerraf (What Numbers Could Not Be [1965]) by Crispin Wright - Frege's Concept of Numbers as Objects 3.xv | |
A reaction: He cites Dedekind (and hence the Peano Axioms) as the source of this. The interest is that progression seems to be fundamental to ordianls, but this claims it is also fundamental to cardinals. Note that in the first instance they are finite. |
17904 | A set has k members if it one-one corresponds with the numbers less than or equal to k [Benacerraf] |
Full Idea: Any set has k members if and only if it can be put into one-to-one correspondence with the set of numbers less than or equal to k. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], I) | |
A reaction: This is 'Ernie's' view of things in the paper. This defines the finite cardinal numbers in terms of the finite ordinal numbers. He has already said that the set of numbers is well-ordered. |
17906 | To explain numbers you must also explain cardinality, the counting of things [Benacerraf] |
Full Idea: I would disagree with Quine. The explanation of cardinality - i.e. of the use of numbers for 'transitive counting', as I have called it - is part and parcel of the explication of number. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], I n2) | |
A reaction: Quine says numbers are just a progression, with transitive counting as a bonus. Interesting that Benacerraf identifies cardinality with transitive counting. I would have thought it was the possession of numerical quantity, not ascertaining it. |
9898 | We can count intransitively (reciting numbers) without understanding transitive counting of items [Benacerraf] |
Full Idea: Learning number words in the right order is counting 'intransitively'; using them as measures of sets is counting 'transitively'. ..It seems possible for someone to learn the former without learning the latter. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], I) | |
A reaction: Scruton's nice question (Idea 3907) is whether you could be said to understand numbers if you could only count intransitively. I would have thought such a state contained no understanding at all of numbers. Benacerraf agrees. |
17903 | Someone can recite numbers but not know how to count things; but not vice versa [Benacerraf] |
Full Idea: It seems that it is possible for someone to learn to count intransitively without learning to count transitively. But not vice versa. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], I) | |
A reaction: Benacerraf favours the priority of the ordinals. It is doubtful whether you have grasped cardinality properly if you don't know how to count things. Could I understand 'he has 27 sheep', without understanding the system of natural numbers? |
9897 | The application of a system of numbers is counting and measurement [Benacerraf] |
Full Idea: The application of a system of numbers is counting and measurement. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], I) | |
A reaction: A simple point, but it needs spelling out. Counting seems prior, in experience if not in logic. Measuring is a luxury you find you can indulge in (by imagining your quantity) split into parts, once you have mastered counting. |
9900 | For Zermelo 3 belongs to 17, but for Von Neumann it does not [Benacerraf] |
Full Idea: Ernie's number progression is [φ],[φ,[φ]],[φ,[φ],[φ,[φ,[φ]]],..., whereas Johnny's is [φ],[[φ]],[[[φ]]],... For Ernie 3 belongs to 17, not for Johnny. For Ernie 17 has 17 members; for Johnny it has one. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], II) | |
A reaction: Benacerraf's point is that there is no proof-theoretic way to choose between them, though I am willing to offer my intuition that Ernie (Zermelo) gives the right account. Seventeen pebbles 'contains' three pebbles; you must pass 3 to count to 17. |
9899 | The successor of x is either x and all its members, or just the unit set of x [Benacerraf] |
Full Idea: For Ernie, the successor of a number x was the set consisting of x and all the members of x, while for Johnny the successor of x was simply [x], the unit set of x - the set whose only member is x. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], II) | |
A reaction: See also Idea 9900. Benacerraf's famous point is that it doesn't seem to make any difference to arithmetic which version of set theory you choose as its basis. I take this to conclusively refute the idea that numbers ARE sets. |
8697 | Disputes about mathematical objects seem irrelevant, and mathematicians cannot resolve them [Benacerraf, by Friend] |
Full Idea: If two children were brought up knowing two different set theories, they could entirely agree on how to do arithmetic, up to the point where they discuss ontology. There is no mathematical way to tell which is the true representation of numbers. | |
From: report of Paul Benacerraf (What Numbers Could Not Be [1965]) by Michèle Friend - Introducing the Philosophy of Mathematics | |
A reaction: Benacerraf ends by proposing a structuralist approach. If mathematics is consistent with conflicting set theories, then those theories are not shedding light on mathematics. |
8304 | No particular pair of sets can tell us what 'two' is, just by one-to-one correlation [Benacerraf, by Lowe] |
Full Idea: Hume's Principle can't tell us what a cardinal number is (this is one lesson of Benacerraf's well-known problem). An infinity of pairs of sets could actually be the number two (not just the simplest sets). | |
From: report of Paul Benacerraf (What Numbers Could Not Be [1965]) by E.J. Lowe - The Possibility of Metaphysics 10.3 | |
A reaction: The drift here is for numbers to end up as being basic, axiomatic, indefinable, universal entities. Since I favour patterns as the basis of numbers, I think the basis might be in a pre-verbal experience, which even a bird might have, viewing its eggs. |
9906 | If ordinal numbers are 'reducible to' some set-theory, then which is which? [Benacerraf] |
Full Idea: If a particular set-theory is in a strong sense 'reducible to' the theory of ordinal numbers... then we can still ask, but which is really which? | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], IIIB) | |
A reaction: A nice question about all reductions. If we reduce mind to brain, does that mean that brain is really just mind. To have a direction (up/down?), reduction must lead to explanation in a single direction only. Do numbers explain sets? |
9907 | If any recursive sequence will explain ordinals, then it seems to be the structure which matters [Benacerraf] |
Full Idea: If any recursive sequence whatever would do to explain ordinal numbers suggests that what is important is not the individuality of each element, but the structure which they jointly exhibit. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], IIIC) | |
A reaction: This sentence launched the whole modern theory of Structuralism in mathematics. It is hard to see what properties a number-as-object could have which would entail its place in an ordinal sequence. |
9908 | The job is done by the whole system of numbers, so numbers are not objects [Benacerraf] |
Full Idea: 'Objects' do not do the job of numbers singly; the whole system performs the job or nothing does. I therefore argue that numbers could not be objects at all. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], IIIC) | |
A reaction: This thought is explored by structuralism - though it is a moot point where mere 'nodes' in a system (perhaps filled with old bits of furniture) will do the job either. No one ever explains the 'power' of numbers (felt when you do a sudoku). Causal? |
9909 | The number 3 defines the role of being third in a progression [Benacerraf] |
Full Idea: Any object can play the role of 3; that is, any object can be the third element in some progression. What is peculiar to 3 is that it defines that role, not by being a paradigm, but by representing the relation of any third member of a progression. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], IIIC) | |
A reaction: An interesting early attempt to spell out the structuralist idea. I'm thinking that the role is spelled out by the intersection of patterns which involve threes. |
9911 | Number words no more have referents than do the parts of a ruler [Benacerraf] |
Full Idea: Questions of the identification of the referents of number words should be dismissed as misguided in just the way that a question about the referents of the parts of a ruler would be seen as misguided. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], IIIC) | |
A reaction: What a very nice simple point. It would be very strange to insist that every single part of the continuum of a ruler should be regarded as an 'object'. |
8925 | Mathematical objects only have properties relating them to other 'elements' of the same structure [Benacerraf] |
Full Idea: Mathematical objects have no properties other than those relating them to other 'elements' of the same structure. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], p.285), quoted by Fraser MacBride - Structuralism Reconsidered §3 n13 | |
A reaction: Suppose we only had one number - 13 - and we all cried with joy when we recognised it in a group of objects. Would that be a number, or just a pattern, or something hovering between the two? |
9938 | How can numbers be objects if order is their only property? [Benacerraf, by Putnam] |
Full Idea: Benacerraf raises the question how numbers can be 'objects' if they have no properties except order in a particular ω-sequence. | |
From: report of Paul Benacerraf (What Numbers Could Not Be [1965], p.301) by Hilary Putnam - Mathematics without Foundations | |
A reaction: Frege certainly didn't think that order was their only property (see his 'borehole' metaphor in Grundlagen). It might be better to say that they are objects which only have relational properties. |
9910 | Number-as-objects works wholesale, but fails utterly object by object [Benacerraf] |
Full Idea: The identification of numbers with objects works wholesale but fails utterly object by object. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], IIIC) | |
A reaction: This seems to be a glaring problem for platonists. You can stare at 1728 till you are blue in the face, but it only begins to have any properties at all once you examine its place in the system. This is unusual behaviour for an object. |
9903 | Number words are not predicates, as they function very differently from adjectives [Benacerraf] |
Full Idea: The unpredicative nature of number words can be seen by noting how different they are from, say, ordinary adjectives, which do function as predicates. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], II) | |
A reaction: He points out that 'x is seventeen' is a rare construction in English, unlike 'x is happy/green/interesting', and that numbers outrank all other adjectives (having to appear first in any string of them). |
19295 | Add Hume's principle to logic, to get numbers; arithmetic truths rest on the nature of the numbers [Hale] |
Full Idea: The existence of the natural numbers is not a matter of pure logic - it cannot be proved in pure logic. It can be proved in second-order logic plus Hume's principle. Truths of arithmetic are not logic - they depend on the nature of natural numbers. | |
From: Bob Hale (Necessary Beings [2013], 07.4) | |
A reaction: Hume's principles needs entities which can be matched to one another, so a certain ontology is needed to get neo-logicism off the ground. |
9904 | The set-theory paradoxes mean that 17 can't be the class of all classes with 17 members [Benacerraf] |
Full Idea: In no consistent theory is there a class of all classes with seventeen members. The existence of the paradoxes is a good reason to deny to 'seventeen' this univocal role of designating the class of all classes with seventeen members. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], II) | |
A reaction: This was Frege's disaster, and seems to block any attempt to achieve logicism by translating numbers into sets. It now seems unclear whether set theory is logic, or mathematics, or sui generis. |
19281 | Interesting supervenience must characterise the base quite differently from what supervenes on it [Hale] |
Full Idea: Any intereresting supervenience thesis requires that the class of facts on which the allegedly supervening facts supervene be characterizable independently, without use or presupposition of the notions involved in stating the supervening facts. | |
From: Bob Hale (Necessary Beings [2013], 03.4.1) | |
A reaction: There might be intermediate cases here, since having descriptions which are utterly unconnected (at any level) might be rather challenging. |
19278 | There is no gap between a fact that p, and it is true that p; so we only have the truth-condtions for p [Hale] |
Full Idea: There is no clear gap between its being a fact that p and its being true that p, no obvious way to individuate the fact a true statement records other than via that statement's truth-conditions. | |
From: Bob Hale (Necessary Beings [2013], 03.2) | |
A reaction: Typical of philosophers of language. The concept of a fact is of something mind-independent; the concept of a truth is of something mind-dependent. They can't therefore be the same thing (by the contrapositive of the indiscernability of identicals!). |
19302 | If a chair could be made of slightly different material, that could lead to big changes [Hale] |
Full Idea: How shall we prevent a sorites taking us to the conclusion that a chair might have originated in a completely disjoint lot of wood, or even in some other material altogether? | |
From: Bob Hale (Necessary Beings [2013], 11.3.7) | |
A reaction: This seems a good criticism of Kripke's implausible claim that his lectern is necessarily (or essentially) made of the piece of wood it is made of. Could his lectern have had a small piece of plastic inserted in it? |
9905 | Identity statements make sense only if there are possible individuating conditions [Benacerraf] |
Full Idea: Identity statements make sense only in contexts where there exist possible individuating conditions. | |
From: Paul Benacerraf (What Numbers Could Not Be [1965], III) | |
A reaction: He is objecting to bizarre identifications involving numbers. An identity statement may be bizarre even if we can clearly individuate the two candidates. Winston Churchill is a Mars Bar. Identifying George Orwell with Eric Blair doesn't need a 'respect'. |
19290 | Absolute necessities are necessarily necessary [Hale] |
Full Idea: I argue that any absolute necessity is necessarily necessary. | |
From: Bob Hale (Necessary Beings [2013], 05.5.2) | |
A reaction: This requires the principle of S4 modal logic, that necessity implies necessary necessity. He argues that S5 is the logical of absolute necessity. |
19286 | 'Absolute necessity' is when there is no restriction on the things which necessitate p [Hale] |
Full Idea: The strength of the claim that p is 'absolutely necessary' derives from the fact that in its expression as a universally quantified counterfactual ('everything will necessitate p'), the quantifier ranges over all propositions whatever. | |
From: Bob Hale (Necessary Beings [2013], 04.1) | |
A reaction: Other philosophers don't seem to use the term 'absolute necessity', but it seems a useful concept, in contrast to conditional or local necessities. You can't buy chocolate on the sun. |
19288 | Logical and metaphysical necessities differ in their vocabulary, and their underlying entities [Hale] |
Full Idea: The difference between logical and metaphysical necessities lies, not in the range of possibilities for which they hold, but - at the linguistic level - in the kind of vocabulary essential to their expression, and the kinds of entities that explain them. | |
From: Bob Hale (Necessary Beings [2013], 04.5) | |
A reaction: I don't think much of the idea that the difference is just linguistic, and I don't like the idea of 'entities' as grounding them. I see logical necessities as arising from natural deduction rules, and metaphysical ones coming from the nature of reality. |
19285 | Logical necessity is something which is true, no matter what else is the case [Hale] |
Full Idea: We can identify the belief that the proposition that p is logically necessary, where p may be of any logical form, with the belief that, no matter what else was the case, it would be true that p. | |
From: Bob Hale (Necessary Beings [2013], 04.1) | |
A reaction: I find this surprising. I take it that logical necessity must be the consequence of logic. That all squares have corners doesn't seem to be a matter of logic. But then he seems to expand logical necessity to include conceptual necessity. Why? |
19287 | Maybe each type of logic has its own necessity, gradually becoming broader [Hale] |
Full Idea: We can distinguish between narrower and broader kinds of logical necessity. There are, for example, the logical necessities of propostional logic, those of first-order logic, and so on. Maybe they are necessities expressed using logical vocabulary. | |
From: Bob Hale (Necessary Beings [2013], 04.5) | |
A reaction: Hale goes on to prefer a view that embraces conceptual necessities. I think in philosophy we should designate the necessities according to their sources. This might clarify a currently rather confused situation. First-order includes propositional logic. |
19282 | It seems that we cannot show that modal facts depend on non-modal facts [Hale] |
Full Idea: I think we may conclude that there is no significant version of modal supervenience which both commands acceptance and implies that all modal facts depend asymmetrically on non-modal ones. | |
From: Bob Hale (Necessary Beings [2013], 03.4.3) | |
A reaction: This is the conclusion of a sustained and careful discussion, recorded here for interest. I'm inclined to think that there are very few, if any, non-modal facts in the world, if those facts are accurately characterised. |
19276 | The big challenge for essentialist views of modality is things having necessary existence [Hale] |
Full Idea: Whether the essentialist theory can account for all absolute necessities depends in part on whether the theory can explain the necessities of existence (of certain objects, properties and entities). | |
From: Bob Hale (Necessary Beings [2013], Intro) | |
A reaction: Hale has a Fregean commitment to all sorts of abstract objects, and then finds difficulty in explaining them from his essentialist viewpoint. His book didn't convince me. I'm more of a nominalist, me, so I sleep better at nights. |
19293 | Essentialism doesn't explain necessity reductively; it explains all necessities in terms of a few basic natures [Hale] |
Full Idea: The point of the essentialist theory is not to provide a reductive explanation of necessities. It is, rather, to locate a base class of necessities - those which directly reflect the natures of things - in terms of which the remainder may be explained. | |
From: Bob Hale (Necessary Beings [2013], 06.6) | |
A reaction: My picture is of most of the necessities being directly explained by the natures of things, rather than a small core of natures generating all the derived ones. All the necessities of squares derive from the nature of the square. |
19294 | If necessity derives from essences, how do we explain the necessary existence of essences? [Hale] |
Full Idea: If the essentialist theory of necessity is to be adequate, it must be able to explain how the existence of certain objects - such as the natural numbers - can itself be absolutely necessary. | |
From: Bob Hale (Necessary Beings [2013], 07.1) | |
A reaction: Hale and his neo-logicist pals think that numbers are 'objects', and they necessarily exist, so he obviously has a problem. I don't see any alternative for essentialists to treating the existing (and possible) natures as brute facts. |
19279 | What are these worlds, that being true in all of them makes something necessary? [Hale] |
Full Idea: We need an explanation of what worlds are that makes clear why being true at all of them should be necessary and sufficient for being necessary (and true at one of them suffices for being possible). | |
From: Bob Hale (Necessary Beings [2013], 03.3.2) | |
A reaction: Hale is introducing combinatorial accounts of worlds, as one possible answer to this. Hale observes that all the worlds might be identical to our world. It is always assumed that the worlds are hugely varied. But maybe worlds are constrained. |
19299 | Possible worlds make every proposition true or false, which endorses classical logic [Hale] |
Full Idea: The standard conception of worlds incorporates the assumption of bivalence - every proposition is either true or false. But it is infelicitous to build into one's basic semantic machinery a principle endorsing classical logic against its rivals. | |
From: Bob Hale (Necessary Beings [2013], 10.3) | |
A reaction: No wonder Dummett (with his intuitionist logic) immediately spurned possible worlds. This objection must be central to many recent thinkers who have begun to doubt possible worlds. I heard Kit Fine say 'always kick possible worlds where you can'. |
19300 | The molecules may explain the water, but they are not what 'water' means [Hale] |
Full Idea: What it is to be (pure) water is to be explained in terms of being composed of H2O molecules, but this is not what the word 'water' means. | |
From: Bob Hale (Necessary Beings [2013], 11.2) | |
A reaction: Hale says when the real and verbal definitions match, we can know the essence a priori. If they come apart, presumably we need a posteriori research. Interesting. It is certainly dubious to say a stuff-word means its chemical composition. |
7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |
Full Idea: The six perfections are of giving, morality, patience, vigour, meditation, and wisdom. | |
From: Nagarjuna (Mahaprajnaparamitashastra [c.120], 88) | |
A reaction: What is 'morality', if giving is not part of it? I like patience and vigour being two of the virtues, which immediately implies an Aristotelian mean (which is always what is 'appropriate'). |