13 ideas
| 21239 | Philosophers are marked by a joint love of evidence and ambiguity [Merleau-Ponty] |
| Full Idea: The philosopher is marked by the distinguishing trait that he possesses inseparably the taste for evidence and the feeling for ambiguity. | |
| From: Maurice Merleau-Ponty (In Praise of Philosophy [1953], p.4), quoted by Sarah Bakewell - At the Existentialist Café 11 | |
| A reaction: I strongly approve of the idea that philosophers are primarily interested in evidence (rather than reason or logic), and I also like the idea that the ambiguous evidence is the most interesting. The mind looks physical and non-physical. |
| 18755 | Validity is explained as truth in all models, because that relies on the logical terms [McGee] |
| Full Idea: A model of a language assigns values to non-logical terms. If a sentence is true in every model, its truth doesn't depend on those non-logical terms. Hence the validity of an argument comes from its logical form. Thus models explain logical validity. | |
| From: Vann McGee (Logical Consequence [2014], 4) | |
| A reaction: [compressed] Thus you get a rigorous account of logical validity by only allowing the rigorous input of model theory. This is the modern strategy of analytic philosophy. But is 'it's red so it's coloured' logically valid? |
| 18751 | Natural language includes connectives like 'because' which are not truth-functional [McGee] |
| Full Idea: Natural language includes connectives that are not truth-functional. In order for 'p because q' to be true, both p and q have to be true, but knowing the simpler sentences are true doesn't determine whether the larger sentence is true. | |
| From: Vann McGee (Logical Consequence [2014], 2) |
| 18761 | Second-order variables need to range over more than collections of first-order objects [McGee] |
| Full Idea: To get any advantage from moving to second-order logic, we need to assign to second-order variables a role different from merely ranging over collections made up of things the first-order variables range over. | |
| From: Vann McGee (Logical Consequence [2014], 7) | |
| A reaction: Thus it is exciting if they range over genuine properties, but not so exciting if you merely characterise those properties as sets of first-order objects. This idea leads into a discussion of plural quantification. |
| 18753 | An ontologically secure semantics for predicate calculus relies on sets [McGee] |
| Full Idea: We can get a less ontologically perilous presentation of the semantics of the predicate calculus by using sets instead of concepts. | |
| From: Vann McGee (Logical Consequence [2014], 4) | |
| A reaction: The perilous versions rely on Fregean concepts, and notably Russell's 'concept that does not fall under itself'. The sets, of course, have to be ontologically secure, and so will involve the iterative conception, rather than naive set theory. |
| 18754 | Logically valid sentences are analytic truths which are just true because of their logical words [McGee] |
| Full Idea: Logically valid sentences are a species of analytic sentence, being true not just in virtue of the meanings of their words, but true in virtue of the meanings of their logical words. | |
| From: Vann McGee (Logical Consequence [2014], 4) | |
| A reaction: A helpful link between logical truths and analytic truths, which had not struck me before. |
| 18757 | Soundness theorems are uninformative, because they rely on soundness in their proofs [McGee] |
| Full Idea: Soundness theorems are seldom very informative, since typically we use informally, in proving the theorem, the very same rules whose soundness we are attempting to establish. | |
| From: Vann McGee (Logical Consequence [2014], 5) | |
| A reaction: [He cites Quine 1935] |
| 18760 | The culmination of Euclidean geometry was axioms that made all models isomorphic [McGee] |
| Full Idea: One of the culminating achievements of Euclidean geometry was categorical axiomatisations, that describe the geometric structure so completely that any two models of the axioms are isomorphic. The axioms are second-order. | |
| From: Vann McGee (Logical Consequence [2014], 7) | |
| A reaction: [He cites Veblen 1904 and Hilbert 1903] For most mathematicians, categorical axiomatisation is the best you can ever dream of (rather than a single true axiomatisation). |
| 21862 | Consciousness is based on 'I can', not on 'I think' [Merleau-Ponty] |
| Full Idea: Consciousness is in the first place not a matter of 'I think' but of 'I can'. | |
| From: Maurice Merleau-Ponty (Phenomenology of Perception [1945], p.159), quoted by Beth Lord - Spinoza's Ethics 2 'Sensation' | |
| A reaction: The point here (quoted during a discussion of Spinoza) is that you can't leave out the role of the body, which seems correct. |
| 20750 | The mind does not unite perceptions, because they flow into one another [Merleau-Ponty] |
| Full Idea: I do not have one perception, then another, and between them a link brought about by the mind. Rather, each perspective merges into the other [against a unified background]. | |
| From: Maurice Merleau-Ponty (Phenomenology of Perception [1945], p.329-30), quoted by Kevin Aho - Existentialism: an introduction 3 'Perceptual' | |
| A reaction: I take this to be another piece of evidence pointing to realism as the best explanation of experience. A problem for Descartes is what unites the sequence of thoughts. |
| 14644 | If my conception of pain derives from me, it is a contradiction to speak of another's pain [Malcolm] |
| Full Idea: If I obtain my conception of pain from pain that I experience, then it will be a part of my conception of pain that I am the only being that can experience it. For me it will be contradiction to speak of another's pain. | |
| From: Norman Malcolm (Wittgenstein's 'Philosophical Investigations' [1954]), quoted by Alvin Plantinga - De Re and De Dicto p.44 | |
| A reaction: This obviously has the private language argument in the background. It seems to point towards a behaviourist view, that I derive pain from external behaviour in the first instance. So how do I connect the behaviour to the feeling? |
| 18762 | A maxim claims that if we are allowed to assert a sentence, that means it must be true [McGee] |
| Full Idea: If our linguistic conventions entitle us to assert a sentence, they thereby make it true, because of the maxim that 'truth is the norm of assertion'. | |
| From: Vann McGee (Logical Consequence [2014], 8) | |
| A reaction: You could only really deny that maxim if you had no belief at all in truth, but then you can assert anything you like (with full entitlement). Maybe you can assert anything you like as long as it doesn't upset anyone? Etc. |
| 1422 | God's existence is either necessary or impossible, and no one has shown that the concept of God is contradictory [Malcolm] |
| Full Idea: God's existence is either impossible or necessary. It can be the former only if the concept of such a being is self-contradictory or in some way logically absurd. Assuming that this is not so, it follows that He necessarily exists. | |
| From: Norman Malcolm (Anselm's Argument [1959], §2) | |
| A reaction: The concept of God suggests paradoxes of omniscience, omnipotence and free will, so self-contradiction seems possible. How should we respond if the argument suggests God is necessary, but evidence suggests God is highly unlikely? |