18 ideas
| 11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
| Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
| A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
| 11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
| Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
| From: Ian Rumfitt ("Yes" and "No" [2000]) | |
| A reaction: This is the standard view which Rumfitt sets out to challenge. |
| 11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
| Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
| A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
| 1507 | We don't have time for infinite quantity, but we do for infinite divisibility, because time is also divisible [Aristotle on Zeno of Elea] |
| Full Idea: Although it is impossible to make contact in a finite time with things that are infinite in quantity, it is possible to do so with things that are infinitely divisible, since the time itself is also infinite in this way. | |
| From: comment on Zeno (Elea) (fragments/reports [c.450 BCE], A25) by Aristotle - Physics 233a21 |
| 5109 | The fast runner must always reach the point from which the slower runner started [Zeno of Elea, by Aristotle] |
| Full Idea: Zeno's so-called 'Achilles' claims that the slowest runner will never be caught by the fastest runner, because the one behind has first to reach the point from which the one in front started, and so the slower one is bound always to be in front. | |
| From: report of Zeno (Elea) (fragments/reports [c.450 BCE]) by Aristotle - Physics 239b14 | |
| A reaction: The point is that the slower runner will always have moved on when the faster runner catches up with the starting point. We must understand how humble the early Greeks felt when they confronted arguments like this. It was like a divine revelation. |
| 4261 | The Lottery Paradox says each ticket is likely to lose, so there probably won't be a winner [Bonjour, by PG] |
| Full Idea: The Lottery Paradox says that for 100 tickets and one winner, each ticket has a .99 likelihood of defeat, so they are all likely to lose, so there is unlikely to be a winner. | |
| From: report of Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], §5) by PG - Db (ideas) | |
| A reaction: The problem seems to be viewing each ticket in isolation. If I buy two tickets, I increase my chances of winning. |
| 1512 | Zeno is wrong that one grain of millet makes a sound; why should one grain achieve what the whole bushel does? [Aristotle on Zeno of Elea] |
| Full Idea: Zeno is wrong in arguing that the tiniest fragment of millet makes a sound; there is no reason why the fragment should be able to move in any amount of time the air which the whole bushel moved as it fell. | |
| From: comment on Zeno (Elea) (fragments/reports [c.450 BCE], A29) by Aristotle - Physics 250a16 |
| 1508 | Zeno's arrow paradox depends on the assumption that time is composed of nows [Aristotle on Zeno of Elea] |
| Full Idea: Zeno's third argument claims that a moving arrow is still. Here the conclusion depends on assuming that time is composed of nows; if this assumption is not granted, the argument fails. | |
| From: comment on Zeno (Elea) (fragments/reports [c.450 BCE], A27?) by Aristotle - Physics 239b5 |
| 4255 | Externalist theories of knowledge are one species of foundationalism [Bonjour] |
| Full Idea: Externalist theories of knowledge are one species of foundationalism. | |
| From: Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], Intro) | |
| A reaction: I don't see why there shouldn't be a phenomenalist, anti-realist version of externalism, which just has 'starting points' instead of a serious commitment to foundations. |
| 4257 | The big problem for foundationalism is to explain how basic beliefs are possible [Bonjour] |
| Full Idea: The fundamental question that must be answered by any acceptable version of foundationalism is: how are basic beliefs possible? | |
| From: Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], §I) | |
| A reaction: This question seems to be asking for a justification for basic beliefs, which smacks of 'Who made God?' Look, basic beliefs are just basic, right? |
| 4256 | The main argument for foundationalism is that all other theories involve a regress leading to scepticism [Bonjour] |
| Full Idea: The central argument for foundationalism is simply that all other possible outcomes of the regress of justifications lead inexorably to scepticism. | |
| From: Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], §I) | |
| A reaction: If you prefer coherence to foundations, you need the security of reason to assess the coherence (which seems to be an internal foundation!). |
| 4258 | Extreme externalism says no more justification is required than the truth of the belief [Bonjour] |
| Full Idea: The most extreme version of externalism would be one that held that the external condition required for justification is simply the truth of the belief in question. | |
| From: Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], §II) | |
| A reaction: The question is, why should we demand any more than this? The problem case is, traditionally, the lucky guess, but naturalist may say that these just don't occur with any regularity. We only get beliefs right because they are true. |
| 4259 | External reliability is not enough, if the internal state of the believer is known to be irrational [Bonjour] |
| Full Idea: External or objective reliability is not enough to offset subjective irrationality (such as unexplained clairvoyance). | |
| From: Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], §IV) | |
| A reaction: A good argument. Where do animals fit into this? If your clairvoyance kept working, in the end you might concede that you 'knew', even though you were baffled about how you managed it. |
| 4260 | Even if there is no obvious irrationality, it may be irrational to base knowledge entirely on external criteria [Bonjour] |
| Full Idea: It may be that where there are no positive grounds for a charge of irrationality, the acceptance of a belief with only external justification is still subjectively irrational in a sense that rules out its being epistemologically justified. | |
| From: Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], §IV) | |
| A reaction: A key objection. Surely rational behaviour requires a judgement to be made before a belief is accepted? If you are consistently clairvoyant, you must ask why. |
| 11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
| Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
| A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |
| 454 | If there are many things they must have a finite number, but there must be endless things between them [Zeno of Elea] |
| Full Idea: It things are many, they can't be more or less than they are, so they must be finite, but also there must be endless things between each thing, so they must be infinite. | |
| From: Zeno (Elea) (fragments/reports [c.450 BCE], B3), quoted by Simplicius - On Aristotle's 'Physics' 140.29 |
| 455 | That which moves, moves neither in the place in which it is, nor in that in which it is not [Zeno of Elea] |
| Full Idea: That which moves, moves neither in the place in which it is, nor in that in which it is not. | |
| From: Zeno (Elea) (fragments/reports [c.450 BCE], B4), quoted by (who?) - where? |
| 1511 | If everything is in a place, what is the place in? Place doesn't exist [Zeno of Elea, by Simplicius] |
| Full Idea: If there is a place it will be in something, because everything that exists is in something. But what is in something is in a place. Therefore the place will be in a place, and so on ad infinitum. Therefore, there is no such thing as place. | |
| From: report of Zeno (Elea) (fragments/reports [c.450 BCE], B3) by Simplicius - On Aristotle's 'Physics' 9.562.3 |