34 ideas
| 1553 | No perceptible object is truly straight or curved [Protagoras] |
| Full Idea: No perceptible object is geometrically straight or curved; after all, a circle does not touch a ruler at a point, as Protagoras used to say, in arguing against the geometers. | |
| From: Protagoras (fragments/reports [c.441 BCE], B07), quoted by Aristotle - Metaphysics 998a1 |
| 8780 | Attributes are functions, not objects; this distinguishes 'square of 2' from 'double of 2' [Geach] |
| Full Idea: Attributes should not be thought of as identifiable objects. It is better to follow Frege and compare them to mathematical functions. 'Square of' and 'double of' x are distinct functions, even though they are not distinguishable in thought when x is 2. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §11) | |
| A reaction: Attributes are features of the world, of which animals are well aware, and the mathematical model is dubious when dealing with physical properties. The route to arriving at 2 is not the same concept as 2. There are many roads to Rome. |
| 11910 | Being 'the same' is meaningless, unless we specify 'the same X' [Geach] |
| Full Idea: "The same" is a fragmentary expression, and has no significance unless we say or mean "the same X", where X represents a general term. ...There is no such thing as being just 'the same'. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §16) | |
| A reaction: Geach seems oddly unaware of the perfect identity of Hespherus with Phosphorus. His critics don't spot that he was concerned with identity over time (of 'the same man', who ages). Perry's critique emphasises the type/token distinction. |
| 1549 | Everything that exists consists in being perceived [Protagoras] |
| Full Idea: Everything that exists consists in being perceived. | |
| From: Protagoras (fragments/reports [c.441 BCE]), quoted by Didymus the Blind - Commentary on the Psalms (frags) | |
| A reaction: A striking anticipation of Berkeley's "esse est percipi" (to be is to be perceived). |
| 1545 | Protagoras was the first to claim that there are two contradictory arguments about everything [Protagoras, by Diog. Laertius] |
| Full Idea: Protagoras was the first to claim that there are two contradictory arguments about everything. | |
| From: report of Protagoras (fragments/reports [c.441 BCE], A01) by Diogenes Laertius - Lives of Eminent Philosophers 09.51 |
| 1547 | Man is the measure of all things - of things that are, and of things that are not [Protagoras] |
| Full Idea: He began one of his books as follows: 'Man is the measure of all things - of the things that are, that they are, and of the things that are not, that they are not'. | |
| From: Protagoras (fragments/reports [c.441 BCE], B01), quoted by Diogenes Laertius - Lives of Eminent Philosophers 09.51 |
| 3305 | There is no more purely metaphysical doctrine than Protagorean relativism [Benardete,JA on Protagoras] |
| Full Idea: No purer metaphysical doctrine can possibly be found than the Protagorean thesis that to be (anything at all) is to be relative ( to something or other). | |
| From: comment on Protagoras (fragments/reports [c.441 BCE]) by José A. Benardete - Metaphysics: the logical approach Ch.3 |
| 3313 | If my hot wind is your cold wind, then wind is neither hot nor cold, and so not as cold as itself [Benardete,JA on Protagoras] |
| Full Idea: Because the wind is cold to me but not you, Protagoras takes it to in itself neither cold nor not-cold. Accordingly, I very much doubt that he can allow the wind to be exactly as cold as itself. | |
| From: comment on Protagoras (fragments/reports [c.441 BCE]) by José A. Benardete - Metaphysics: the logical approach Ch.8 |
| 3317 | You can only state the problem of the relative warmth of an object by agreeing on the underlying object [Benardete,JA on Protagoras] |
| Full Idea: Only if the thing that is cold to me is precisely identical with the thing that is not cold to you can Protagoras launch his argument, but then it is seen to be the thing in itself that exists absolutely speaking. | |
| From: comment on Protagoras (fragments/reports [c.441 BCE]) by José A. Benardete - Metaphysics: the logical approach Ch.8 |
| 247 | God is "the measure of all things", more than any man [Plato on Protagoras] |
| Full Idea: In our view it is God who is pre-eminently the "measure of all things", much more so than any "man", as they say. | |
| From: comment on Protagoras (fragments/reports [c.441 BCE]) by Plato - The Laws 716c |
| 612 | Relativists think if you poke your eye and see double, there must be two things [Aristotle on Protagoras] |
| Full Idea: In fact there is no difference between Protagoreanism and saying this: if you stick your finger under your eyes and make single things seem two, then they are two, just because they seem to be two. | |
| From: comment on Protagoras (fragments/reports [c.441 BCE]) by Aristotle - Metaphysics 1063a06 |
| 606 | Protagoras absurdly thought that the knowing or perceiving man is 'the measure of all things' [Aristotle on Protagoras] |
| Full Idea: When Protagoras quipped that man is the measure of all things, he had in mind, of course, the knowing or perceiving man. The grounds are that they have perception/knowledge, and these are said to be the measures of objects. Utter nonsense! | |
| From: comment on Protagoras (fragments/reports [c.441 BCE]) by Aristotle - Metaphysics 1053b |
| 8775 | A big flea is a small animal, so 'big' and 'small' cannot be acquired by abstraction [Geach] |
| Full Idea: A big flea or rat is a small animal, and a small elephant is a big animal, so there can be no question of ignoring the kind of thing to which 'big' or 'small' is referred and forming those concepts by abstraction. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §9) | |
| A reaction: Geach is attacking a caricature of the theory. Abstraction is a neat mental trick which has developed in stages, from big rats relative to us, to big relative to other rats, to the concept of 'relative' (Idea 8776!), to the concept of 'relative bigness'. |
| 8776 | We cannot learn relations by abstraction, because their converse must be learned too [Geach] |
| Full Idea: Abstractionists are unaware of the difficulty with relations - that they neither exist nor can be observed apart from the converse relation, the two being indivisible, as in grasping 'to the left of' and 'to the right of'. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §9) | |
| A reaction: It is hard to see how a rival account such as platonism could help. It seems obvious to me that 'right' and 'left' would be quite meaningless without some experience of things in space, including an orientation to them. |
| 2567 | You can't define real mental states in terms of behaviour that never happens [Geach] |
| Full Idea: We can't take a statement that two men, whose overt behaviour was not actually different, were in different states of mind as being really a statement that the behaviour of one man would have been different in hypothetical circumstances that never arose. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §3) | |
| A reaction: This is the whole problem with trying to define the mind as dispositions. The same might be said of properties, since some properties are active, but others are mere potential or disposition. Hence 'process' looks to me the most promising word for mind. |
| 2568 | Beliefs aren't tied to particular behaviours [Geach] |
| Full Idea: Is there any behaviour characteristic of a given belief? | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §4) | |
| A reaction: Well, yes. Belief that a dog is about to bite you. Belief that this nice food is yours, and you are hungry. But he has a good point. He is pointing out that the mental state is a very different thing from the 'disposition' to behave in a certain way. |
| 8781 | The mind does not lift concepts from experience; it creates them, and then applies them [Geach] |
| Full Idea: Having a concept is not recognizing a feature of experience; the mind makes concepts. We then fit our concepts to experience. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §11) | |
| A reaction: This seems to imply that we create concepts ex nihilo, which is a rather worse theory than saying that we abstract them from multiple (and multi-level) experiences. That minds create concepts is a truism. How do we do it? |
| 8769 | If someone has aphasia but can still play chess, they clearly have concepts [Geach] |
| Full Idea: If a man struck with aphasia can still play bridge or chess, I certainly wish to say he still has the concepts involved in the game, although he can no longer exercise them verbally. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §5) | |
| A reaction: Geach proceeds thereafter to concentrate on language, but this caveat is crucial. To suggest that concepts are entirely verbal has always struck me as ridiculous, and an insult to our inarticulate mammalian cousins. |
| 8770 | 'Abstractionism' is acquiring a concept by picking out one experience amongst a group [Geach] |
| Full Idea: I call 'abstractionism' the doctrine that a concept is acquired by a process of singling out in attention some one feature given in direct experience - abstracting it - and ignoring the other features simultaneously given - abstracting from them. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §6) | |
| A reaction: Locke seems to be the best known ancestor of this view, and Geach launches a vigorous attack against it. However, contemporary philosophers still refer to the process, and I think Geach should be crushed and this theory revived. |
| 8771 | 'Or' and 'not' are not to be found in the sensible world, or even in the world of inner experience [Geach] |
| Full Idea: Nowhere in the sensible world could you find anything to be suitably labelled 'or' or 'not'. So the abstractionist appeals to an 'inner sense', or hesitation for 'or', and of frustration or inhibition for 'not'. Personally I see a threat in 'or else'! | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §7) | |
| A reaction: This is a key argument of Geach's against abstractionism. As a logician he prefers to discuss connectives rather than, say, colours. I think they might be meta-abstractions, which you create internally once you have picked up the knack. |
| 8772 | We can't acquire number-concepts by extracting the number from the things being counted [Geach] |
| Full Idea: The number-concepts just cannot be got by concentrating on the number and abstracting from the kind of things being counted. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §8) | |
| A reaction: This point is from Frege - that if you 'abstract away' everything apart from the number, you are simply left with nothing in experience. The objection might, I think, be met by viewing it as second-order abstraction, perhaps getting to a pattern first. |
| 8773 | Abstractionists can't explain counting, because it must precede experience of objects [Geach] |
| Full Idea: The way counting is learned is wholly contrary to abstractionist preconceptions, because the series of numerals has to be learned before it can be applied. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §8) | |
| A reaction: You might learn to parrot the names of numbers, but you could hardly know what they meant if you couldn't count anything. See Idea 3907. I would have thought that individuating objects must logically and pedagogically precede counting. |
| 8774 | The numbers don't exist in nature, so they cannot have been abstracted from there into our languages [Geach] |
| Full Idea: The pattern of the numeral series that is grasped by a child exists nowhere in nature outside human languages, so the human race cannot possibly have discerned this pattern by abstracting it from some natural context. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §8) | |
| A reaction: This is a spectacular non sequitur, which begs the question. Abstractionists precisely claim that the process of abstraction brings numerals into human language from the natural context. Structuralism is an attempt to explain the process. |
| 8778 | Blind people can use colour words like 'red' perfectly intelligently [Geach] |
| Full Idea: It is not true that men born blind can form no colour-concepts; a man born blind can use the word 'red' with a considerable measure of intelligence; he can show a practical grasp of the logic of the word. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §10) | |
| A reaction: Weak. It is obvious that they pick up the word 'red' from the usage of sighted people, and the usage of the word doesn't guarantee a grasp of the concept, as when non-mathematicians refer to 'calculus'. Compare Idea 7377 and Idea 7866. |
| 8777 | If 'black' and 'cat' can be used in the absence of such objects, how can such usage be abstracted? [Geach] |
| Full Idea: Since we can use the terms 'black' and 'cat' in situations not including any black object or any cat, how could this part of the use be got by abstraction? | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §10) | |
| A reaction: [He is attacking H.H. Price] It doesn't seem a huge psychological leap to apply the word 'cat' when we remember a cat, and once it is in the mind we can play games with our abstractions. Cats are smaller than dogs. |
| 8779 | We can form two different abstract concepts that apply to a single unified experience [Geach] |
| Full Idea: It is impossible to form the concept of 'chromatic colour' by discriminative attention to a feature given in my visual experience. In seeing a red window-pane, I do not have two sensations, one of redness and one of chromatic colour. | |
| From: Peter Geach (Mental Acts: their content and their objects [1957], §10) | |
| A reaction: Again Geach begs the question, because abstractionists claim that you can focus on two different 'aspects' of the one experience, as that it is a 'window', or it is 'red', or it is not a wall, or it is not monochrome. |
| 6016 | Early sophists thought convention improved nature; later they said nature was diminished by it [Protagoras, by Miller,FD] |
| Full Idea: Protagoras and Hippias evidently believed that convention was an improvement on nature, whereas later sophists such as Antiphon, Thrasymachus and Callicles seemed to contend that conventional morality was undermined because it was 'against nature'. | |
| From: report of Protagoras (fragments/reports [c.441 BCE]) by Fred D. Miller jr - Classical Political Thought | |
| A reaction: This gets to the heart of a much more interesting aspect of the nomos-physis (convention-nature) debate, rather than just a slanging match between relativists and the rest. The debate still goes on, over issues about the free market and intervention. |
| 1580 | For Protagoras the only bad behaviour is that which interferes with social harmony [Protagoras, by Roochnik] |
| Full Idea: For Protagoras the only constraint on human behaviour is that it not interfere with social harmony, the essential condition for human survival. | |
| From: report of Protagoras (fragments/reports [c.441 BCE]) by David Roochnik - The Tragedy of Reason p.63 |
| 205 | Protagoras contradicts himself by saying virtue is teachable, but then that it is not knowledge [Plato on Protagoras] |
| Full Idea: Protagoras claimed that virtue was teachable, but now tries to show it is not knowledge, which makes it less likely to be teachable. | |
| From: comment on Protagoras (fragments/reports [c.441 BCE]) by Plato - Protagoras 361b |
| 1659 | Protagoras seems to have made the huge move of separating punishment from revenge [Protagoras, by Vlastos] |
| Full Idea: The distinction of punishment from revenge must be regarded as one of the most momentous of the conceptual discoveries ever made by humanity in the course of its slow, tortuous, precarious, emergence from barbaric tribalism. Protagoras originated it. | |
| From: report of Protagoras (fragments/reports [c.441 BCE]) by Gregory Vlastos - Socrates: Ironist and Moral Philosopher p.187 |
| 532 | Successful education must go deep into the soul [Protagoras] |
| Full Idea: Education does not take root in the soul unless one goes deep. | |
| From: Protagoras (fragments/reports [c.441 BCE], B11), quoted by Plutarch - On Practice 178.25 |
| 1552 | He spent public money on education, as it benefits the individual and the state [Protagoras, by Diodorus of Sicily] |
| Full Idea: He used legislation to improve the condition of illiterate people, on the grounds that they lack one of life's great goods, and thought literacy should be a matter of public concern and expense. | |
| From: report of Protagoras (fragments/reports [c.441 BCE]) by Diodorus of Sicily - Universal History 12.13.3.3 |
| 15877 | The aim of science is just to create a comprehensive, elegant language to describe brute facts [Poincaré, by Harré] |
| Full Idea: In Poincaré's view, we try to construct a language within which the brute facts of experience are expressed as comprehensively and as elegantly as possible. The job of science is the forging of a language precisely suited to that purpose. | |
| From: report of Henri Poincaré (The Value of Science [1906], Pt III) by Rom Harré - Laws of Nature 2 | |
| A reaction: I'm often struck by how obscure and difficult our accounts of self-evident facts can be. Chairs are easy, and the metaphysics of chairs is hideous. Why is that? I'm a robust realist, but I like Poincaré's idea. He permits facts. |
| 1551 | He said he didn't know whether there are gods - but this is the same as atheism [Diogenes of Oen. on Protagoras] |
| Full Idea: He said that he did not know whether there were gods - but this is the same as saying that he knew there were no gods. | |
| From: comment on Protagoras (fragments/reports [c.441 BCE], A23) by Diogenes (Oen) - Wall inscription 11 Chil 2 |