30 ideas
| 23367 | Even pointing a finger should only be done for a reason [Epictetus] |
| Full Idea: Philosophy says it is not right even to stretch out a finger without some reason. | |
| From: Epictetus (fragments/reports [c.57], 15) | |
| A reaction: The key point here is that philosophy concerns action, an idea on which Epictetus is very keen. He rather despise theory. This idea perfectly sums up the concept of the wholly rational life (which no rational person would actually want to live!). |
| 2352 | The job of the philosopher is to distinguish facts about the world from conventions [Putnam] |
| Full Idea: It is the job of the philosopher to distinguish what is fact and what is convention in our theorising about the world. | |
| From: Hilary Putnam (Representation and Reality [1988], §7 p.112) | |
| A reaction: This may well be the entire truth about philosophy. It begins with the Nomos-Physis debate in ancient Athens, and it turns out to be the key issue in almost every area of metaphysics, epistemology, aesthetics and morality. |
| 2345 | Semantic notions do not occur in Tarski's definitions, but assessing their correctness involves translation [Putnam] |
| Full Idea: Although no semantic notions are used in Tarski's truth definitions themselves, they are used in deciding when such a definition is correct, namely the notion of translation. | |
| From: Hilary Putnam (Representation and Reality [1988], §4 p.66) |
| 2347 | Asserting the truth of an indexical statement is not the same as uttering the statement [Putnam] |
| Full Idea: If you say "I am going to drive this car", and I say "That's true", that is very different from my saying "I am going to drive this car". | |
| From: Hilary Putnam (Representation and Reality [1988], §4 p.68) |
| 9193 | ZF set theory has variables which range over sets, 'equals' and 'member', and extensionality [Dummett] |
| Full Idea: ZF set theory is a first-order axiomatization. Variables range over sets, there are no second-order variables, and primitive predicates are just 'equals' and 'member of'. The axiom of extensionality says sets with the same members are identical. | |
| From: Michael Dummett (The Philosophy of Mathematics [1998], 7) | |
| A reaction: If the eleven members of the cricket team are the same as the eleven members of the hockey team, is the cricket team the same as the hockey team? Our cricket team is better than our hockey team, so different predicates apply to them. |
| 9194 | The main alternative to ZF is one which includes looser classes as well as sets [Dummett] |
| Full Idea: The main alternative to ZF is two-sorted theories, with some variables ranging over classes. Classes have more generous existence assumptions: there is a universal class, containing all sets, and a class containing all ordinals. Classes are not members. | |
| From: Michael Dummett (The Philosophy of Mathematics [1998], 7.1.1) | |
| A reaction: My intuition is to prefer strict systems when it comes to logical theories. The whole point is precision. Otherwise we could just think about things, and skip all this difficult symbolic stuff. |
| 9195 | Intuitionists reject excluded middle, not for a third value, but for possibility of proof [Dummett] |
| Full Idea: It must not be concluded from the rejection of excluded middle that intuitionistic logic operates with three values: true, false, and neither true nor false. It does not make use of true and false, but only with a construction being a proof. | |
| From: Michael Dummett (The Philosophy of Mathematics [1998], 8.1) | |
| A reaction: This just sounds like verificationism to me, with all its problems. It seems to make speculative statements meaningless, which can't be right. Realism has lots of propositions which are assumed to be true or false, but also unknowable. |
| 9186 | First-order logic concerns objects; second-order adds properties, kinds, relations and functions [Dummett] |
| Full Idea: First-order logic is distinguished by generalizations (quantification) only over objects: second-order logic admits generalizations or quantification over properties or kinds of objects, and over relations between them, and functions defined over them. | |
| From: Michael Dummett (The Philosophy of Mathematics [1998], 3.1) | |
| A reaction: Second-order logic was introduced by Frege, but is (interestingly) rejected by Quine, because of the ontological commitments involved. I remain unconvinced that quantification entails ontological commitment, so I'm happy. |
| 9187 | Logical truths and inference are characterized either syntactically or semantically [Dummett] |
| Full Idea: There are two ways of characterizing logical truths and correct inference. Proof-theoretic or syntactic characterizations, if the formalization admits of proof or derivation; and model-theoretic or semantic versions, being true in all interpretations. | |
| From: Michael Dummett (The Philosophy of Mathematics [1998], 3.1) | |
| A reaction: Dummett calls this distinction 'fundamental'. The second one involves truth, and hence meaning, where the first one just responds to rules. ..But how can you have a notion of correctly following a rule, without a notion of truth? |
| 9191 | Ordinals seem more basic than cardinals, since we count objects in sequence [Dummett] |
| Full Idea: It can be argued that the notion of ordinal numbers is more fundamental than that of cardinals. To count objects, we must count them in sequence. ..The theory of ordinals forms the substratum of Cantor's theory of cardinals. | |
| From: Michael Dummett (The Philosophy of Mathematics [1998], 5) | |
| A reaction: Depends what you mean by 'fundamental'. I would take cardinality to be psychologically prior ('that is a lot of sheep'). You can't order people by height without first acquiring some people with differing heights. I vote for cardinals. |
| 9192 | The number 4 has different positions in the naturals and the wholes, with the same structure [Dummett] |
| Full Idea: The number 4 cannot be characterized solely by its position in a system, because it has different positions in the system of natural numbers and that of the positive whole numbers, whereas these systems have the very same structure. | |
| From: Michael Dummett (The Philosophy of Mathematics [1998], 6.1) | |
| A reaction: Dummett seems to think this is fairly decisive against structuralism. There is also the structure of the real numbers. We will solve this by saying that the wholes are abstracted from the naturals, which are abstracted from the reals. Job done. |
| 2349 | Realists believe truth is correspondence, independent of humans, is bivalent, and is unique [Putnam] |
| Full Idea: Metaphysical realism about truth is a bundle of ideas: that it is a matter of Correspondence, that it exhibits Independence (of humans), Bivalence, and Uniqueness (there is only one ultimate truth). | |
| From: Hilary Putnam (Representation and Reality [1988], §7 p.107) |
| 2351 | Aristotle says an object (e.g. a lamp) has identity if its parts stay together when it is moved [Putnam] |
| Full Idea: The parts of a lamp stay together when it is moved (which is one of Aristotle's criteria for objecthood). | |
| From: Hilary Putnam (Representation and Reality [1988], §7 p.110) | |
| A reaction: Metaphysics 1052a26 (just after the cross-reference) says a thing may be unified 'if its movement is single'. |
| 2331 | Functionalism says robots and people are the same at one level of abstraction [Putnam] |
| Full Idea: My "functionalism" insisted that a robot, a human being, a silicon creature and a disembodied spirit could all work much the same way when described at the relevant level of abstraction, and it is wrong to think the essence of mind is hardware. | |
| From: Hilary Putnam (Representation and Reality [1988], Int p.xii) | |
| A reaction: This is the key point about the theory - that it is an abstract theory of mind, saying nothing about substances. It drew, however, some misguided criticisms suggesting silly implementations. |
| 2071 | If concepts have external meaning, computational states won't explain psychology [Putnam] |
| Full Idea: Computational models of the brain/mind will not suffice for cognitive psychology. We cannot individuate concepts and beliefs without reference to the environment. Meanings aren't "in the head". | |
| From: Hilary Putnam (Representation and Reality [1988], p.73) | |
| A reaction: Mr Functionalism quits! |
| 2332 | Functionalism can't explain reference and truth, which are needed for logic [Putnam] |
| Full Idea: Functionalism has as much trouble with physical accounts of reference as of meaning. Reference is the main tool used in formal theories of truth. But 'truth' isn't folk psychology, it is central to logic, which everyone wants. | |
| From: Hilary Putnam (Representation and Reality [1988], Int p.xiv) | |
| A reaction: All logic is defined in terms of truth and falsehood resulting from reasoning, but it could be that 'true' and 'false' have no more content that 1 and 0 in binary electronics. They are distinct, but empty. |
| 2348 | Is there just one computational state for each specific belief? [Putnam] |
| Full Idea: The idea that there is one computational state that every being who believes that there are lots of cats in the neighbourhood is in must be false. | |
| From: Hilary Putnam (Representation and Reality [1988], §5 p.84) | |
| A reaction: It is tempting to say that the mental states of such people must have SOMETHING in common, until you realise that all you can specify is that all their states are about cats. |
| 2344 | If we are going to eliminate folk psychology, we must also eliminate folk logic [Putnam] |
| Full Idea: Why don't the eliminationists speak of "folk logic" as well as "folk psychology"? | |
| From: Hilary Putnam (Representation and Reality [1988], §4 p.60) | |
| A reaction: I think Putnam considers that if you can prove 'truth' to be a necessary feature of mental life, that connects mind and world, but marking a sentence as 'T' doesn't make any connections. |
| 2074 | Can we give a scientific, computational account of folk psychology? [Putnam] |
| Full Idea: The desire that grips Fodor, as it once gripped me, is the desire to make belief-desire psychology "scientific" by simply identifying it outright with computational psychology. | |
| From: Hilary Putnam (Representation and Reality [1988], p.7) | |
| A reaction: An "outright" identification looks very implausible. It seems that we should accept that belief-desire psychology is a very good guide to normal brain events, but a bad guide to unusual brain events. See Ideas 2987 and 7519. |
| 2343 | Reference may be different while mental representation is the same [Putnam] |
| Full Idea: The 'mental representations' of Earth speakers and Twin Earth speakers were not in any way different; the reference was different because the substances were different. Reference is fixed by the environment itself. | |
| From: Hilary Putnam (Representation and Reality [1988], §2 p.32) | |
| A reaction: There seems to be an elementary distinction here between what you think you are referring to, and what you are in fact referring to. "That man is the Prince of Wales" (pointing at the butler). |
| 2346 | Meaning and translation (which are needed to define truth) both presuppose the notion of reference [Putnam] |
| Full Idea: The notion of meaning, and hence of translation (needed to define truth), presupposes the notion of reference. | |
| From: Hilary Putnam (Representation and Reality [1988], §4 p.67) | |
| A reaction: It is plausible to see reference as the fundamental notion of language. With no anchors in reality, language would be 'private', in LW's sense. |
| 2354 | "Meaning is use" is not a definition of meaning [Putnam] |
| Full Idea: "Meaning is use" is not a definition of meaning. | |
| From: Hilary Putnam (Representation and Reality [1988], §7 p.119) | |
| A reaction: I agree. It probably fails to define meaning because it is false. A corkscrew is not the action of opening a wine bottle. |
| 2336 | Holism seems to make fixed definition more or less impossible [Putnam] |
| Full Idea: Holism immediately suggests that most terms cannot be defined, at least not in a way that is fixed once and for all. | |
| From: Hilary Putnam (Representation and Reality [1988], §1 p.09) | |
| A reaction: Perhaps there exists a single perfect definition for each holistic system, only graspable by a transcendent intellect. Or why can't there be a matching holistic system of definitions? |
| 2334 | Meaning holism tried to show that you can't get fixed meanings built out of observation terms [Putnam] |
| Full Idea: The doctrine of Quine called "meaning holism" offered arguments refuting logical positivist attempts to show that every term we can understand can be defined using a limited group of "observation terms". | |
| From: Hilary Putnam (Representation and Reality [1988], §1 p.08) | |
| A reaction: To seems a rather large jump from saying that sentences come in groups to full-blown 'holism' (involving every sentence). |
| 2335 | Understanding a sentence involves background knowledge and can't be done in isolation [Putnam] |
| Full Idea: If I say "Hawks fly", I do not intend my hearer to deduce that a hawk with a broken wing will fly. What we expect depends on the whole network of belief. Language describes experience as a network, not sentence by sentence. | |
| From: Hilary Putnam (Representation and Reality [1988], §1 p.09) | |
| A reaction: The shortcut through this is 'exactly what did you mean when you said "Hawks fly"?'. That is, get me closer to your proposition. |
| 2340 | We should separate how the reference of 'gold' is fixed from its conceptual content [Putnam] |
| Full Idea: The effect of my account, as of Kripke's, is to separate the question of how the reference of terms such as 'gold' is fixed from the question of their conceptual content. | |
| From: Hilary Putnam (Representation and Reality [1988], §2 p.38) | |
| A reaction: Too simple. 'Gold' isn't a proper name, like 'Hilary', which needs no more content than a serial number. Baptising a gold sample needs much more information than baptising a person. |
| 2341 | Like names, natural kind terms have their meaning fixed by extension and reference [Putnam] |
| Full Idea: It seems that the dominant "component" of natural kind words is the extension. The referential factor does almost all the work, and natural kind terms resemble names. | |
| From: Hilary Putnam (Representation and Reality [1988], §3 p.49) | |
| A reaction: My concept of 'tiger' does not mainly consist of the tigers. Does the concept contract as the tiger population dwindles? Prototypes, exemplars etc. See 'Concepts' |
| 2339 | Aristotle implies that we have the complete concepts of a language in our heads, but we don't [Putnam] |
| Full Idea: What is wrong with the Aristotelian picture (of meaning and reference based on concepts) is that it suggest that everything that is necessary for the use of language is stored in each individual mind, but no individual language works this way. | |
| From: Hilary Putnam (Representation and Reality [1988], §2 p.25) | |
| A reaction: Languages must partly work that way. You can't talk without a conceptual storehouse. In a small society I would expect every adult to know the full vocabulary. |
| 2338 | Reference (say to 'elms') is a social phenomenon which we can leave to experts [Putnam] |
| Full Idea: Reference is a social phenomenon. Individual speakers do not have to know how to distinguish robins, or elms, or aluminium. They can always rely on experts to do this for them. | |
| From: Hilary Putnam (Representation and Reality [1988], §2 p.22) | |
| A reaction: It can't just be a social phenomenon. The experts don't just enquire about standard usage, or defer to Hilary Putnam. |
| 2342 | "Water" is a natural kind term, but "H2O" is a description [Putnam] |
| Full Idea: "Water" functions as a natural kind term, but "H2O" is a description, synonymous with an account of its atoms. | |
| From: Hilary Putnam (Representation and Reality [1988], §3 p.50) |