24 ideas
| 7396 | Hobbes created English-language philosophy [Hobbes, by Tuck] |
| Full Idea: Hobbes created English-language philosophy. | |
| From: report of Thomas Hobbes (The Elements of Law [1640]) by Richard Tuck - Hobbes Pref | |
| A reaction: Tuck mentions Hooker as a predecessor in jurisprudence. Otherwise, an impressive label. |
| 18951 | For scientific purposes there is a precise concept of 'true-in-L', using set theory [Putnam] |
| Full Idea: For a language L there is a predicate 'true-in-L' which one can employ for all scientific purposes in place of intuitive truth, and this predicate admits of a precise definition using only the vocabulary of L itself plus set theory. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.2) | |
| A reaction: He refers, of course, to Tarski's theory. I'm unclear of the division between 'scientific purposes' and the rest of life (which is why some people embrace 'minimal' theories of ordinary truth). I'm struck by set theory being a necessary feature. |
| 18953 | Modern notation frees us from Aristotle's restriction of only using two class-names in premises [Putnam] |
| Full Idea: In modern notation we can consider potential logical principles that Aristotle never considered because of his general practice of looking at inferences each of whose premises involved exactly two class-names. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.3) | |
| A reaction: Presumably you can build up complex inferences from a pair of terms, just as you do with pairs in set theory. |
| 18949 | The universal syllogism is now expressed as the transitivity of subclasses [Putnam] |
| Full Idea: On its modern interpretation, the validity of the inference 'All S are M; All M are P; so All S are P' just expresses the transitivity of the relation 'subclass of'. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.1) | |
| A reaction: A simple point I've never quite grasped. Since lots of syllogisms can be expressed as Venn Diagrams, in which the circles are just sets, it's kind of obvious really. So why does Sommers go back to 'terms'? See 'Term Logic'. |
| 18952 | '⊃' ('if...then') is used with the definition 'Px ⊃ Qx' is short for '¬(Px & ¬Qx)' [Putnam] |
| Full Idea: The symbol '⊃' (read 'if...then') is used with the definition 'Px ⊃ Qx' ('if Px then Qx') is short for '¬(Px & ¬Qx)'. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.3) | |
| A reaction: So ⊃ and → are just abbreviations, and not really a proper part of the language. Notoriously, though, this is quite a long way from what 'if...then' means in ordinary English, and it leads to paradoxical oddities. |
| 18958 | In type theory, 'x ∈ y' is well defined only if x and y are of the appropriate type [Putnam] |
| Full Idea: In the theory of types, 'x ∈ y' is well defined only if x and y are of the appropriate type, where individuals count as the zero type, sets of individuals as type one, sets of sets of individuals as type two. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.6) |
| 18954 | Before the late 19th century logic was trivialised by not dealing with relations [Putnam] |
| Full Idea: It was essentially the failure to develop a logic of relations that trivialised the logic studied before the end of the nineteenth century. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.3) | |
| A reaction: De Morgan, Peirce and Frege were, I believe, the people who put this right. |
| 18956 | Asserting first-order validity implicitly involves second-order reference to classes [Putnam] |
| Full Idea: The natural understanding of first-order logic is that in writing down first-order schemata we are implicitly asserting their validity, that is, making second-order assertions. ...Thus even quantification theory involves reference to classes. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.3) | |
| A reaction: If, as a nominalist, you totally rejected classes, presumably you would get by in first-order logic somehow. To say 'there are no classes so there is no logical validity' sounds bonkers. |
| 18962 | Unfashionably, I think logic has an empirical foundation [Putnam] |
| Full Idea: Today, the tendency among philosophers is to assume that in no sense does logic itself have an empirical foundation. I believe this tendency is wrong. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.9) | |
| A reaction: I agree, not on the basis of indispensability to science, but on the basis of psychological processes that lead from experience to logic. Russell and Quine are Putnam's allies here, and Frege is his opponent. Putnam developed a quantum logic. |
| 18961 | We can identify functions with certain sets - or identify sets with certain functions [Putnam] |
| Full Idea: Instead of identifying functions with certain sets, I might have identified sets with certain functions. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.9) |
| 18955 | Having a valid form doesn't ensure truth, as it may be meaningless [Putnam] |
| Full Idea: I don't think all substitution-instances of a valid schema are 'true'; some are clearly meaningless, such as 'If all boojums are snarks and all snarks are egglehumphs, then all boojums are egglehumphs'. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.3) | |
| A reaction: This seems like a very good challenge to Quine's claim that it is only form which produces a logical truth. Keep deductive and semantic consequence separate, with two different types of 'logical truth'. |
| 18959 | Sets larger than the continuum should be studied in an 'if-then' spirit [Putnam] |
| Full Idea: Sets of a very high type or very high cardinality (higher than the continuum, for example) should today be investigated in an 'if-then' spirit. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.7) | |
| A reaction: This attitude goes back to Hilbert, but it fits with Quine's view of what is indispensable for science. It is hard to see a reason for the cut-off, just looking at the logic of expanding sets. |
| 18957 | Nominalism only makes sense if it is materialist [Putnam] |
| Full Idea: Nominalists must at heart be materialists, or so it seems to me: otherwise their scruples are unintelligible. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.5) | |
| A reaction: This is modern nominalism - the rejection of abstract objects. I largely plead guilty to both charges. |
| 18950 | Physics is full of non-physical entities, such as space-vectors [Putnam] |
| Full Idea: Physics is full of references to such 'non-physical' entities as state-vectors, Hamiltonians, Hilbert space etc. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.2) | |
| A reaction: I take these to be concepts which are 'abstracted' from the physical facts, and so they don't strike me as being much of an ontological problem, or an objection to nominalism (which Putnam takes them to be). |
| 16638 | The qualities of the world are mere appearances; reality is the motions which cause them [Hobbes] |
| Full Idea: Whatsoever accidents or qualities our senses make us think there be in the world, they are not there, but are seemings and apparitions only. The things that really are in the world without us are those motions by which these seemings are caused. | |
| From: Thomas Hobbes (The Elements of Law [1640], I.2.10), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 10.2 | |
| A reaction: This seems to count as a sense-datum theory, rather than a representative theory of perception, since it makes no commitment to the qualities containing any accurate information at all. We just start from the qualities and try to work it out. |
| 16688 | Evidence is conception, which is imagination, which proceeds from the senses [Hobbes] |
| Full Idea: All evidence is conception, as it is said, and all conception is imagination and proceeds from sense. And spirits we suppose to be those substances which work not upon the sense, and therefore not conceptible. | |
| From: Thomas Hobbes (The Elements of Law [1640], I.11.5), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 16.2 | |
| A reaction: This is exactly the same as Hume's claim that all ideas are the result of impressions, and is the very essence of empiricism. We see here that such an epistemology can have huge consequences. |
| 7405 | Experience can't prove universal truths [Hobbes] |
| Full Idea: Experience concludeth nothing universally. | |
| From: Thomas Hobbes (The Elements of Law [1640], I.4.10), quoted by Richard Tuck - Hobbes Ch.2 | |
| A reaction: Empiricists seem proud to claim this limitation on human understanding, where rationalists like Leibniz use it as an argument against empiricism. Kripke says (e.g. Idea 4966) they are both wrong! I sympathise with Kripke. |
| 18960 | Most predictions are uninteresting, and are only sought in order to confirm a theory [Putnam] |
| Full Idea: Scientists want successful predictions in order to confirm their theories; they do not want theories in order to obtain the predictions, which are in some cases of not the slightest interest in themselves. | |
| From: Hilary Putnam (Philosophy of Logic [1971], Ch.8) | |
| A reaction: Equally, we might only care about the prediction, and have no interest at all in the theory. Farmers want weather predictions, not a PhD in meteorology. |
| 7408 | It is an error that reason should control the passions, which give right guidance on their own [Hobbes, by Tuck] |
| Full Idea: Hobbes (and Descartes, and many contemporaries) argued that the traditional idea that reason should control the passions was an error, and that (properly understood) our emotions would guide us in the right direction. | |
| From: report of Thomas Hobbes (The Elements of Law [1640]) by Richard Tuck - Hobbes Ch.2 | |
| A reaction: I'm an intellectualist on this one. It strikes me as rather naïve and romantic to think that unthinking emotion could ever consistently approach what is right. A recipe for disaster. |
| 7407 | Good and evil are what please us; goodness and badness the powers causing them [Hobbes] |
| Full Idea: We call good and evil the things that please and displease us; and so we call goodness and badness, the qualities of powers whereby they do it. | |
| From: Thomas Hobbes (The Elements of Law [1640], I.7.3), quoted by Richard Tuck - Hobbes Ch.2 | |
| A reaction: It is pointed out by Tuck that this is just like his treatment of colour terms (values as secondary qualities). I would have thought it was obvious that I could say 'x pleases me, although I disapprove of it' (e.g. black humour). |
| 21378 | We clearly feel responsible for our deeds, because we are quite certain that we did them [Schopenhauer] |
| Full Idea: Another fact of consciousness ...is the wholly clear and certain feeling of responsibility for what we do, of the accountability of our actions, which rests on the unshakable certainty that we ourselves are the doers of our deeds. | |
| From: Arthur Schopenhauer (On the Freedom of the Will [1841], p.93-4), quoted by Christopher Janaway - Schopenhauer 7 'Freedom' | |
| A reaction: The point is that we have this feeling even if we do not believe in free will. I am struck by the fact that responsibility is very obvious in our own case, even if it is not when we objectively consider other people. Even villains can feel guilty. |
| 7410 | Self-preservation is basic, and people judge differently about that, implying ethical relativism [Hobbes, by Tuck] |
| Full Idea: If men are their own judges of what conduces to their preservation, ..all men make different decisions about what counts as a danger, so (for Hobbes) the grimmest version of ethical relativism seems to be the only possible ethical vision. | |
| From: report of Thomas Hobbes (The Elements of Law [1640]) by Richard Tuck - Hobbes Ch.2 | |
| A reaction: This might depend on self-preservation being the only fundamental value. But if self-preservation is not a pressing issue, presumably other values might come into play, some of them less concerned with the individual's own interests. |
| 7409 | Hobbes shifted from talk of 'the good' to talk of 'rights' [Hobbes, by Tuck] |
| Full Idea: Hobbes (like Grotius) shifted from talking about 'the good', which had been the traditional subject for both ancient and Renaissance moralists, to talking instead about 'rights'. | |
| From: report of Thomas Hobbes (The Elements of Law [1640]) by Richard Tuck - Hobbes Ch.2 | |
| A reaction: This is part of the crucial shift away from the Greek interest in excellence of character, towards the Enlightenment legalistic interest in right actions, as well as social rights. Bad move, well analysed by MacIntyre. |
| 7411 | The attributes of God just show our inability to conceive his nature [Hobbes] |
| Full Idea: All the attributes of God signify our inability and defect of power to conceive any thing concerning his nature. | |
| From: Thomas Hobbes (The Elements of Law [1640], I.10.2), quoted by Richard Tuck - Hobbes Ch.2 | |
| A reaction: Presumably he means that 'omnipotence' should just be translated as 'mind-boggling power'. St Anselm's concept of God (Idea 1405) is helpful here, placing it at the upper limit of what can actually be conceived. |