42 ideas
2056 | Philosophers are always switching direction to something more interesting [Plato] |
Full Idea: Philosophers are always ready to change direction, if a topic crops up which is more attractive than the one to hand. | |
From: Plato (Theaetetus [c.368 BCE], 172d) | |
A reaction: Which sounds trivial, but it may be what God does. |
2086 | Understanding mainly involves knowing the elements, not their combinations [Plato] |
Full Idea: A perfect grasp of any subject depends far more on knowing elements than on knowing complexes. | |
From: Plato (Theaetetus [c.368 BCE], 206b) |
2083 | Either a syllable is its letters (making parts as knowable as whole) or it isn't (meaning it has no parts) [Plato] |
Full Idea: Either a syllable is not the same as its letters, in which case it cannot have the letters as parts of itself, or it is the same as its letters, in which case these basic elements are just as knowable as it is. | |
From: Plato (Theaetetus [c.368 BCE], 205b) |
2082 | A rational account is essentially a weaving together of things with names [Plato] |
Full Idea: Just as primary elements are woven together, so their names may be woven together to produce a spoken account, because an account is essentially a weaving together of names. | |
From: Plato (Theaetetus [c.368 BCE], 202b) | |
A reaction: If justification requires 'logos', and logos is a 'weaving together of names', then Plato might be taken as endorsing the coherence account of justification. Or do the two 'weavings' correspond? |
2052 | Eristic discussion is aggressive, but dialectic aims to help one's companions in discussion [Plato] |
Full Idea: Eristic discussions involve as many tricks and traps as possible, but dialectical discussions involve being serious and correcting the interlocutor's mistakes only when they are his own fault or the result of past conditioning. | |
From: Plato (Theaetetus [c.368 BCE], 167e) |
15854 | A primary element has only a name, and no logos, but complexes have an account, by weaving the names [Plato] |
Full Idea: A primary element cannot be expressed in an account; it can only be named, for a name is all that it has. But with the things composed of these ...just as the elements are woven together, so the names can woven to become an account. | |
From: Plato (Theaetetus [c.368 BCE], 202b01-3) | |
A reaction: This is the beginning of what I see as Aristotle's metaphysics, as derived from his epistemology, that is, ontology is what explains, and what we can give an account [logos] of. Aristotle treats this under 'definitions'. |
17809 | Gödel showed that the syntactic approach to the infinite is of limited value [Kreisel] |
Full Idea: Usually Gödel's incompleteness theorems are taken as showing a limitation on the syntactic approach to an understanding of the concept of infinity. | |
From: Georg Kreisel (Hilbert's Programme [1958], 05) |
17810 | The study of mathematical foundations needs new non-mathematical concepts [Kreisel] |
Full Idea: It is necessary to use non-mathematical concepts, i.e. concepts lacking the precision which permit mathematical manipulation, for a significant approach to foundations. We currently have no concepts of this kind which we can take seriously. | |
From: Georg Kreisel (Hilbert's Programme [1958], 06) | |
A reaction: Music to the ears of any philosopher of mathematics, because it means they are not yet out of a job. |
10216 | We master arithmetic by knowing all the numbers in our soul [Plato] |
Full Idea: It must surely be true that a man who has completely mastered arithmetic knows all numbers? Because there are pieces of knowledge covering all numbers in his soul. | |
From: Plato (Theaetetus [c.368 BCE], 198b) | |
A reaction: This clearly views numbers as objects. Expectation of knowing them all is a bit startling! They also appear to be innate in us, and hence they appear to be Forms. See Aristotle's comment in Idea 645. |
2060 | There seem to be two sorts of change: alteration and motion [Plato] |
Full Idea: There are two kinds of change, I think: alteration and motion. | |
From: Plato (Theaetetus [c.368 BCE], 181d) | |
A reaction: Idea 1700 is better than this. |
2084 | If a word has no parts and has a single identity, it turns out to be the same kind of thing as a letter [Plato] |
Full Idea: If a complex or a syllable has no parts and is a single identity, hasn't it turned out to be the same kind of thing as an element or letter? | |
From: Plato (Theaetetus [c.368 BCE], 205d) |
15844 | A sum is that from which nothing is lacking, which is a whole [Plato] |
Full Idea: But this sum now - isn't it just when there is nothing lacking that it is a sum? Yes, necessarily. And won't this very same thing - that from which nothing is lacking - be a whole? | |
From: Plato (Theaetetus [c.368 BCE], 205a) | |
A reaction: This seems to be right, be rather too vague and potentially circular to be of much use. What is the criterion for deciding that nothing is lacking? |
15843 | The whole can't be the parts, because it would be all of the parts, which is the whole [Plato] |
Full Idea: The whole does not consist of parts; for it did, it would be all the parts and so would be the sum. | |
From: Plato (Theaetetus [c.368 BCE], 204e) | |
A reaction: That is, 'the whole is the sum of its parts' is a tautology! The claim that 'the whole is more than the sum of its parts' gets into similar trouble. See Verity Harte on this. |
2080 | Things are only knowable if a rational account (logos) is possible [Plato] |
Full Idea: Things which are susceptible to a rational account are knowable. | |
From: Plato (Theaetetus [c.368 BCE], 201d) |
16126 | Expertise is knowledge of the whole by means of the parts [Plato] |
Full Idea: A man has passed from mere judgment to expert knowledge of the being of a wagon when he has done so in virtue of having gone over the whole by means of the elements. | |
From: Plato (Theaetetus [c.368 BCE], 207c) | |
A reaction: Plato is emphasising that the expert must know the hundred parts of a wagon, and not just the half dozen main components, but here the point is to go over the whole via the parts, and not just list the parts. |
2050 | It is impossible to believe something which is held to be false [Plato] |
Full Idea: It is impossible to believe something which is not the case. | |
From: Plato (Theaetetus [c.368 BCE], 167a) |
2076 | How can a belief exist if its object doesn't exist? [Plato] |
Full Idea: If the object of a belief is what is not, the object of this belief is nothing; but if there is no object to a belief, then that is not belief at all. | |
From: Plato (Theaetetus [c.368 BCE], 189a) |
2045 | Perception is infallible, suggesting that it is knowledge [Plato] |
Full Idea: Perception is always of something that is, and it is infallible, which suggests that it is knowledge. | |
From: Plato (Theaetetus [c.368 BCE], 152c) |
2067 | Our senses could have been separate, but they converge on one mind [Plato] |
Full Idea: It would be peculiar if each of us were like a Trojan horse, with a whole bunch of senses sitting inside us, rather than that all these perceptions converge onto a single identity (mind, or whatever one ought to call it). | |
From: Plato (Theaetetus [c.368 BCE], 184d) |
6417 | In 1921 Russell abandoned sense-data, and the gap between sensation and object [Russell, by Grayling] |
Full Idea: In 'The Analysis of Mind' Russell gave up talk of 'sense-data', and ceased to distinguish between the act of sensing and what is sensed. | |
From: report of Bertrand Russell (The Analysis of Mind [1921]) by A.C. Grayling - Russell Ch.2 | |
A reaction: This seems to lead towards the modern 'adverbial' account of sensing, where I don't sense 'data', but where qualia (such as redness) are our particular mode of directly perceiving objects, where insects might directly perceive them in a different mode. |
6474 | Seeing is not in itself knowledge, but is separate from what is seen, such as a patch of colour [Russell] |
Full Idea: Undeniably, knowledge comes through seeing, but it is a mistake to regard the mere seeing itself as knowledge; if we are so to regard it, we must distinguish the seeing from what is seen; a patch of colour is one thing, and our seeing it is another. | |
From: Bertrand Russell (The Analysis of Mind [1921], Lec. VIII) | |
A reaction: This is Russell's 1921 explanation of why he adopted sense-data (but he rejects them later in this paragraph). This gives a simplistic impression of what he intended, which has three components: the object, the 'sensibile', and the sense-datum. |
6476 | We cannot assume that the subject actually exists, so we cannot distinguish sensations from sense-data [Russell] |
Full Idea: If we are to avoid a perfectly gratuitous assumption, we must dispense with the subject as one of the actual ingredients of the world; but when we do this, the possibility of distinguishing the sensation from the sense-datum vanishes. | |
From: Bertrand Russell (The Analysis of Mind [1921], Lec. VIII) | |
A reaction: This is the reason why Russell himself rejected sense-data. It is more normal, I think, to reject them simply as being superfluous. If the subject can simply perceive the sense-data, why can't they just perceive the object more directly? |
2068 | With what physical faculty do we perceive pairs of opposed abstract qualities? [Plato] |
Full Idea: With what physical faculty do we perceive being and not-being, similarity and dissimilarity, identity and difference, oneness and many, odd and even and other maths, ….fineness and goodness? | |
From: Plato (Theaetetus [c.368 BCE], 185d) |
2069 | Thought must grasp being itself before truth becomes possible [Plato] |
Full Idea: If you can't apprehend being you can't apprehend truth, and so a thing could not be known. Therefore knowledge is not located in immediate experience but in thinking about it, since the latter makes it possible to grasp being and truth. | |
From: Plato (Theaetetus [c.368 BCE], 186c) |
2078 | You might mistake eleven for twelve in your senses, but not in your mind [Plato] |
Full Idea: Sight or touch might make someone take eleven for twelve, but he could never form this mistaken belief about the contents of his mind. | |
From: Plato (Theaetetus [c.368 BCE], 195e) |
2792 | It is possible the world came into existence five minutes ago, complete with false memories [Russell] |
Full Idea: There is no logical impossibility in the hypothesis that the world sprang into being five minutes ago, exactly as it then was, with a population that "remembered" a wholly unreal past. | |
From: Bertrand Russell (The Analysis of Mind [1921], p.159) | |
A reaction: One of the great sceptical arguments! At a stroke it undermines forever any dreams that memories are totally certain. This is an extra scepticism, which arises if you decide that current experience IS totally certain. |
2089 | An inadequate rational account would still not justify knowledge [Plato] |
Full Idea: If you don't know which letters belong together in the right syllables…it is possible for true belief to be accompanied by a rational account and still not be entitled to the name of knowledge. | |
From: Plato (Theaetetus [c.368 BCE], 208b) | |
A reaction: In each case of justification there is a 'clinching' stage, for which there is never going to be a strict rule. It might be foundational, but equally it might be massive coherence, or no alternative. |
2085 | Parts and wholes are either equally knowable or equally unknowable [Plato] |
Full Idea: Either a syllable and its letters are equally knowable and expressible in a rational account, or they are both equally unknowable and inexpressible. | |
From: Plato (Theaetetus [c.368 BCE], 205e) | |
A reaction: Presumably you could explain the syllable by the letters, but not vice versa, but he must mean that the explanation is worthless without the letters being explained too. So all explanation is worthless? |
2091 | Without distinguishing marks, how do I know what my beliefs are about? [Plato] |
Full Idea: If I only have beliefs about Theaetetus when I don't know his distinguishing mark, how on earth were my beliefs about you rather than anyone else? | |
From: Plato (Theaetetus [c.368 BCE], 209b) | |
A reaction: This is a rather intellectualist approach to mental activity. Presumably Theaetetus has lots of distinguishing marks, but they are not conscious. Must Socrates know everything? |
2087 | A rational account might be seeing an image of one's belief, like a reflection in a mirror [Plato] |
Full Idea: A rational account might be forming an image of one's belief, as in a mirror or a pond. | |
From: Plato (Theaetetus [c.368 BCE], 206d) | |
A reaction: Not promising, since the image is not going to be clearer than the original, or contain any new information. Maybe it would be clarified by being 'framed', instead of drifting in muddle. |
2090 | A rational account involves giving an image, or analysis, or giving a differentiating mark [Plato] |
Full Idea: A third sort of rational account (after giving an image, or analysing elements) is being able to mention some mark which differentiates the object in question ('the sun is the brightest heavenly body'). | |
From: Plato (Theaetetus [c.368 BCE], 208c) | |
A reaction: This is Plato's clearest statement of what would be involved in adding the necessary logos to your true belief. An image of it, or an analysis, or an individuation. How about a cause? |
2081 | Maybe primary elements can be named, but not receive a rational account [Plato] |
Full Idea: Maybe the primary elements of which things are composed are not susceptible to rational accounts. Each of them taken by itself can only be named, but nothing further can be said about it. | |
From: Plato (Theaetetus [c.368 BCE], 201e) | |
A reaction: This still seems to be more or less the central issue in philosophy - which things should be treated as 'primitive', and which other things are analysed and explained using the primitive tools? |
2088 | A rational account of a wagon would mean knowledge of its hundred parts [Plato] |
Full Idea: In the case of a wagon, we may only have correct belief, but someone who is able to explain what it is by going through its hundred parts has got hold of a rational account. | |
From: Plato (Theaetetus [c.368 BCE], 207b) | |
A reaction: A wonderful example. In science, you know smoking correlates with cancer, but you only know it when you know the mechanism, the causal structure. This may be a general truth. |
22326 | Knowledge needs more than a sensitive response; the response must also be appropriate [Russell] |
Full Idea: Accuracy of response to stimulus does not alone show knowledge, but must be reinforced by appropriateness, i.e. suitability of realising one's purpose. | |
From: Bertrand Russell (The Analysis of Mind [1921], p.261), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 66 'Rel' | |
A reaction: The aim of 'realising one's purpose' puts a very pragmatist spin on this. The point is a good one, and seems to apply particularly to Nozick's accurate 'tracking' account of knowledge. |
2047 | What evidence can be brought to show whether we are dreaming or not? [Plato] |
Full Idea: What evidence could be brought if we were asked at this very moment whether we are asleep and are dreaming all our thoughts? | |
From: Plato (Theaetetus [c.368 BCE], 158b) |
2054 | Clearly some people are superior to others when it comes to medicine [Plato] |
Full Idea: In medicine, at least, most people are not self-sufficient at prescribing and effecting cures for themselves, and here some people are superior to others. | |
From: Plato (Theaetetus [c.368 BCE], 171e) |
2053 | If you claim that all beliefs are true, that includes beliefs opposed to your own [Plato] |
Full Idea: To say that everyone believes what is the case, is to concede the truth of the oppositions' beliefs; in other words, the person has to concede that he himself is wrong. | |
From: Plato (Theaetetus [c.368 BCE], 171a) |
2059 | How can a relativist form opinions about what will happen in the future? [Plato] |
Full Idea: Does a relativist have any authority to decide about things which will happen in the future? | |
From: Plato (Theaetetus [c.368 BCE], 178c) | |
A reaction: Nice question! It seems commonsense that such speculations are possible, but without a concept of truth they are ridiculous. |
6475 | In perception, the self is just a logical fiction demanded by grammar [Russell] |
Full Idea: In perception, the idea of the subject appears to be a logical fiction, like mathematical points and instants; it is introduced, not because observation reveals it, but because it is linguistically convenient and apparently demanded by grammar. | |
From: Bertrand Russell (The Analysis of Mind [1921], Lec. VIII) | |
A reaction: In 1912, Russell had felt that both the Cogito, and the experience of meta-thought, had confirmed the existence of a non-permanent ego, but here he offers a Humean rejection. His notion of a 'logical fiction' is behaviouristic. I believe in the Self. |
17811 | The natural conception of points ducks the problem of naming or constructing each point [Kreisel] |
Full Idea: In analysis, the most natural conception of a point ignores the matter of naming the point, i.e. how the real number is represented or by what constructions the point is reached from given points. | |
From: Georg Kreisel (Hilbert's Programme [1958], 13) | |
A reaction: This problem has bothered me. There are formal ways of constructing real numbers, but they don't seem to result in a name for each one. |
2058 | God must be the epitome of goodness, and we can only approach a divine state by being as good as possible [Plato] |
Full Idea: It is impossible for God to be immoral and not to be the acme of morality; and the only way any of us can approximate to God is to become as moral as possible. | |
From: Plato (Theaetetus [c.368 BCE], 176c) |
2057 | There must always be some force of evil ranged against good [Plato] |
Full Idea: The elimination of evil is impossible, Theodorus; there must always be some force ranged against good. | |
From: Plato (Theaetetus [c.368 BCE], 176a) |