12 ideas
| 6259 | Why can't a wise man doubt everything? [Montaigne] |
| Full Idea: Why cannot a wise man dare to doubt anything and everything? | |
| From: Michel de Montaigne (Apology for Raymond Sebond [1580], p.0562) | |
| A reaction: This question seems to be the start of the Enlightenment Project, of attempting to prove everything. MacIntyre warns of the dangers of this in ethical theory. The story of modern philosophy is the discovery of its impossibility. E.g. Davidson on truth. |
| 6263 | No wisdom could make us comfortably walk a wide beam if it was high in the air [Montaigne] |
| Full Idea: Take a beam wide enough to walk along: suspend it between two towers: there is no philosophical wisdom, however firm, which could make us walk along it just as we would if we were on the ground. | |
| From: Michel de Montaigne (Apology for Raymond Sebond [1580], p.0672) | |
| A reaction: This proposes great scepticism about the practical application of philosophical wisdom, but if we talk in terms of the wise assessment of risk in any undertaking, our caution on the raised beam makes perfectly good sense. |
| 6258 | Virtue is the distinctive mark of truth, and its greatest product [Montaigne] |
| Full Idea: The distinctive mark of the Truth we hold ought to be virtue, which is the most exacting mark of Truth, the closest one to heaven and the most worthy thing that Truth produces. | |
| From: Michel de Montaigne (Apology for Raymond Sebond [1580], p.0493) | |
| A reaction: A long way from Tarski and minimalist theories of truth! But not so far from pragmatism. Personally I think Montaigne is making an important claim, which virtue theorists should be attempting to incorporate into their theory. Aristotle would sympathise. |
| 18812 | Split out the logical vocabulary, make an assignment to the rest. It's logical if premises and conclusion match [Tarski, by Rumfitt] |
| Full Idea: Tarski made a division of logical and non-logical vocabulary. He then defined a model as a non-logical assignment satisfying the corresponding sentential function. Then a conclusion follows logically if every model of the premises models the conclusion. | |
| From: report of Alfred Tarski (The Concept of Logical Consequence [1936]) by Ian Rumfitt - The Boundary Stones of Thought 3.2 | |
| A reaction: [compressed] This is Tarski's account of logical consequence, which follows on from his account of truth. 'Logical validity' is then 'true in every model'. Rumfitt doubts whether Tarski has given the meaning of 'logical consequence'. |
| 13344 | X follows from sentences K iff every model of K also models X [Tarski] |
| Full Idea: The sentence X follows logically from the sentences of the class K if and only if every model of the class K is also a model of the sentence X. | |
| From: Alfred Tarski (The Concept of Logical Consequence [1936], p.417) | |
| A reaction: [see Idea 13343 for his account of a 'model'] He is offering to define logical consequence in general, but this definition fits what we now call 'semantic consequence', written |=. This it is standard practice to read |= as 'models'. |
| 13343 | A 'model' is a sequence of objects which satisfies a complete set of sentential functions [Tarski] |
| Full Idea: An arbitrary sequence of objects which satisfies every sentential function of the sentences L' will be called a 'model' or realization of the class L of sentences. There can also be a model of a single sentence is this way. | |
| From: Alfred Tarski (The Concept of Logical Consequence [1936], p.417) | |
| A reaction: [L' is L with the constants replaced by variables] Tarski is the originator of model theory, which is central to modern logic. The word 'realization' is a helpful indicator of what he has in mind. A model begins to look like a possible world. |
| 6262 | We lack some sense or other, and hence objects may have hidden features [Montaigne] |
| Full Idea: We may all lack some sense or other; because of that defect, most of the features of objects may be concealed from us. | |
| From: Michel de Montaigne (Apology for Raymond Sebond [1580], p.0666) | |
| A reaction: This strikes me as simple, straightforward common sense, and right. I cannot make sense of the claim that reality really is just the way it appears. We do not have a built-in neutrino detector, for example. |
| 6260 | Sceptics say there is truth, but no means of making or testing lasting judgements [Montaigne] |
| Full Idea: Pyrrhonians say that truth and falsehood exist; within us we have means of looking for them, but not of making any lasting judgements: we have no touchstone. | |
| From: Michel de Montaigne (Apology for Raymond Sebond [1580], p.0564) | |
| A reaction: This states the key difference between sceptics and relativists. The latter are more extreme as they say there is no such thing as truth. The former concede truth, and their scepticism is about the abilities of human beings. I am an anti-relativist. |
| 6261 | The soul is in the brain, as shown by head injuries [Montaigne] |
| Full Idea: The seat of the powers of the soul is in the brain, as is clearly shown by the fact that wounds and accidents affecting the head immediately harm the faculties of the soul. | |
| From: Michel de Montaigne (Apology for Raymond Sebond [1580], p.0614) | |
| A reaction: At last someone has finally got the facts clear. It seems surprising that the Greeks never clearly grasped this piece of irrefutable evidence - even those Greeks who speculated that the brain was the key. Here we have a fixed fact of philosophy of mind. |
| 3158 | Theories of intentionality presuppose rationality, so can't explain it [Dennett] |
| Full Idea: Intentional theory is vacuous as psychology because it presupposes and does not explain rationality or intelligence. | |
| From: Daniel C. Dennett (Brainstorms:Essays on Mind and Psychology [1978], p.15?) | |
| A reaction: Virtually every philosophical theory seems to founder because it presupposes something like the thing it is meant to explain. I agree that 'intentionality' is a slightly airy concept that would probably reduce to something better. |
| 3159 | Beliefs and desires aren't real; they are prediction techniques [Dennett] |
| Full Idea: Intentional systems don't really have beliefs and desires, but one can explain and predict their behaviour by ascribing beliefs and desires to them. This strategy is pragmatic, not right or wrong. | |
| From: Daniel C. Dennett (Brainstorms:Essays on Mind and Psychology [1978], p.7?) | |
| A reaction: If the ascription of beliefs and desires explains behaviour, then that is good grounds for thinking they might be real features of the brain, and even if that is not so, they are real enough as abstractions from brain events, like the 'economic climate'. |
| 13345 | Sentences are 'analytical' if every sequence of objects models them [Tarski] |
| Full Idea: A class of sentences can be called 'analytical' if every sequence of objects is a model of it. | |
| From: Alfred Tarski (The Concept of Logical Consequence [1936], p.418) | |
| A reaction: See Idea 13344 and Idea 13343 for the context of this assertion. |