41 ideas
23890 | For Plato true wisdom is supernatural [Plato, by Weil] |
Full Idea: It is evident that Plato regards true wisdom as something supernatural. | |
From: report of Plato (works [c.375 BCE]) by Simone Weil - God in Plato p.61 | |
A reaction: Taken literally, I assume this is wrong, but we can empathise with the thought. Wisdom has the feeling of rising above the level of mere knowledge, to achieve the overview I associate with philosophy. |
3060 | Plato never mentions Democritus, and wished to burn his books [Plato, by Diog. Laertius] |
Full Idea: Plato, who mentions nearly all the ancient philosophers, nowhere speaks of Democritus; he wished to burn all of his books, but was persuaded that it was futile. | |
From: report of Plato (works [c.375 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.7.8 |
23891 | Two contradictories force us to find a relation which will correlate them [Plato, by Weil] |
Full Idea: Where contradictions appear there is a correlation of contraries, which is relation. If a contradiction is imposed on the intelligence, it is forced to think of a relation to transform the contradiction into a correlation, which draws the soul higher. | |
From: report of Plato (works [c.375 BCE]) by Simone Weil - God in Plato p.70 | |
A reaction: A much better account of the dialectic than anything I have yet seen in Hegel. For the first time I see some sense in it. A contradiction is not a falsehood, and it must be addressed rather than side-stepped. A kink in the system, that needs ironing. |
13430 | Infinity: there is an infinity of distinguishable individuals [Ramsey] |
Full Idea: The Axiom of Infinity means that there are an infinity of distinguishable individuals, which is an empirical proposition. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], §5) | |
A reaction: The Axiom sounds absurd, as a part of a logical system, but Ramsey ends up defending it. Logical tautologies, which seem to be obviously true, are rendered absurd if they don't refer to any objects, and some of them refer to infinities of objects. |
13428 | Reducibility: to every non-elementary function there is an equivalent elementary function [Ramsey] |
Full Idea: The Axiom of Reducibility asserted that to every non-elementary function there is an equivalent elementary function [note: two functions are equivalent when the same arguments render them both true or both false]. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], §2) | |
A reaction: Ramsey in the business of showing that this axiom from Russell and Whitehead is not needed. He says that the axiom seems to be needed for induction and for Dedekind cuts. Since the cuts rest on it, and it is weak, Ramsey says it must go. |
13427 | Either 'a = b' vacuously names the same thing, or absurdly names different things [Ramsey] |
Full Idea: In 'a = b' either 'a' and 'b' are names of the same thing, in which case the proposition says nothing, or of different things, in which case it is absurd. In neither case is it an assertion of a fact; it only asserts when a or b are descriptions. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], §1) | |
A reaction: This is essentially Frege's problem with Hesperus and Phosphorus. How can identities be informative? So 2+2=4 is extensionally vacuous, but informative because they are different descriptions. |
13334 | Contradictions are either purely logical or mathematical, or they involved thought and language [Ramsey] |
Full Idea: Group A consists of contradictions which would occur in a logical or mathematical system, involving terms such as class or number. Group B contradictions are not purely logical, and contain some reference to thought, language or symbolism. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], p.171), quoted by Graham Priest - The Structure of Paradoxes of Self-Reference 1 | |
A reaction: This has become the orthodox division of all paradoxes, but the division is challenged by Priest (Idea 13373). He suggests that we now realise (post-Tarski?) that language is more involved in logic and mathematics than we thought. |
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. |
13426 | Formalists neglect content, but the logicists have focused on generalizations, and neglected form [Ramsey] |
Full Idea: The formalists neglected the content altogether and made mathematics meaningless, but the logicians neglected the form and made mathematics consist of any true generalisations; only by taking account of both sides can we obtain an adequate theory. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], §1) | |
A reaction: He says mathematics is 'tautological generalizations'. It is a criticism of modern structuralism that it overemphasises form, and fails to pay attention to the meaning of the concepts which stand at the 'nodes' of the structure. |
13425 | Formalism is hopeless, because it focuses on propositions and ignores concepts [Ramsey] |
Full Idea: The hopelessly inadequate formalist theory is, to some extent, the result of considering only the propositions of mathematics and neglecting the analysis of its concepts. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], §1) | |
A reaction: You'll have to read Ramsey to see how this thought pans out, but it at least gives a pointer to how to go about addressing the question. |
14502 | Plato's idea of 'structure' tends to be mathematically expressed [Plato, by Koslicki] |
Full Idea: 'Structure' tends to be characterized by Plato as something that is mathematically expressed. | |
From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects V.3 iv | |
A reaction: [Koslicki is drawing on Verity Harte here] |
20906 | Platonists argue for the indivisible triangle-in-itself [Plato, by Aristotle] |
Full Idea: The Platonists, on the basis of purely logical arguments, posit the existence of an indivisible 'triangle in itself'. | |
From: report of Plato (works [c.375 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 316a15 | |
A reaction: A helpful confirmation that geometrical figures really are among the Forms (bearing in mind that numbers are not, because they contain one another). What shape is the Form of the triangle? |
3039 | When Diogenes said he could only see objects but not their forms, Plato said it was because he had eyes but no intellect [Plato, by Diog. Laertius] |
Full Idea: When Diogenes told Plato he saw tables and cups, but not 'tableness' and 'cupness', Plato replied that this was because Diogenes had eyes but no intellect. | |
From: report of Plato (works [c.375 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 06.2.6 |
17948 | Plato's Forms meant that the sophists only taught the appearance of wisdom and virtue [Plato, by Nehamas] |
Full Idea: Plato's theory of Forms allowed him to claim that the sophists and other opponents were trapped in the world of appearance. What they therefore taught was only apparent wisdom and virtue. | |
From: report of Plato (works [c.375 BCE]) by Alexander Nehamas - Eristic,Antilogic,Sophistic,Dialectic p.118 |
556 | If there is one Form for both the Form and its participants, they must have something in common [Aristotle on Plato] |
Full Idea: If there is the same Form for the Forms and for their participants, then they must have something in common. | |
From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 991a |
563 | If gods are like men, they are just eternal men; similarly, Forms must differ from particulars [Aristotle on Plato] |
Full Idea: We say there is the form of man, horse and health, but nothing else, making the same mistake as those who say that there are gods but that they are in the form of men. They just posit eternal men, and here we are not positing forms but eternal sensibles. | |
From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 997b |
557 | A Form is a cause of things only in the way that white mixed with white is a cause [Aristotle on Plato] |
Full Idea: A Form is a cause of things only in the way that white mixed with white is a cause. | |
From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 991a |
565 | The Forms cannot be changeless if they are in changing things [Aristotle on Plato] |
Full Idea: The Forms could not be changeless if they were in changing things. | |
From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 998a |
9607 | The greatest discovery in human thought is Plato's discovery of abstract objects [Brown,JR on Plato] |
Full Idea: The greatest discovery in the history of human thought is Plato's discovery of abstract objects. | |
From: comment on Plato (works [c.375 BCE]) by James Robert Brown - Philosophy of Mathematics Ch. 2 | |
A reaction: Compare Idea 2860! Given the diametrically opposed views, it is clearly likely that Plato's central view is the most important idea in the history of human thought, even if it is wrong. |
13263 | We can grasp whole things in science, because they have a mathematics and a teleology [Plato, by Koslicki] |
Full Idea: Due to the mathematical nature of structure and the teleological cause underlying the creation of Platonic wholes, these wholes are intelligible, and are in fact the proper objects of science. | |
From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.3 | |
A reaction: I like this idea, because it pays attention to the connection between how we conceive objects to be, and how we are able to think about objects. Only examining these two together enables us to grasp metaphysics. |
13261 | Plato sees an object's structure as expressible in mathematics [Plato, by Koslicki] |
Full Idea: The 'structure' of an object tends to be characterised by Plato as something that is mathematically expressible. | |
From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.3 | |
A reaction: This seems to be pure Pythagoreanism (see Idea 644). Plato is pursuing Pythagoras's research programme, of trying to find mathematics buried in every aspect of reality. |
13265 | Plato was less concerned than Aristotle with the source of unity in a complex object [Plato, by Koslicki] |
Full Idea: Plato was less concerned than Aristotle with the project of how to account, in completely general terms, for the source of unity within a mereologically complex object. | |
From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.5 | |
A reaction: Plato seems to have simply asserted that some sort of harmony held things together. Aristotles puts the forms [eidos] within objects, rather than external, so he has to give a fuller account of what is going on in an object. He never managed it! |
593 | Plato's holds that there are three substances: Forms, mathematical entities, and perceptible bodies [Plato, by Aristotle] |
Full Idea: Plato's doctrine was that the Forms and mathematicals are two substances and that the third substance is that of perceptible bodies. | |
From: report of Plato (works [c.375 BCE]) by Aristotle - Metaphysics 1028b |
13260 | Plato says wholes are either containers, or they're atomic, or they don't exist [Plato, by Koslicki] |
Full Idea: Plato considers a 'container' model for wholes (which are disjoint from their parts) [Parm 144e3-], and a 'nihilist' model, in which only wholes are mereological atoms, and a 'bare pluralities' view, in which wholes are not really one at all. | |
From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.2 | |
A reaction: [She cites Verity Harte for this analysis of Plato] The fourth, and best, seems to be that wholes are parts which fall under some unifying force or structure or principle. |
11237 | Only universals have essence [Plato, by Politis] |
Full Idea: Plato argues that only universals have essence. | |
From: report of Plato (works [c.375 BCE]) by Vassilis Politis - Aristotle and the Metaphysics 1.4 |
11238 | Plato and Aristotle take essence to make a thing what it is [Plato, by Politis] |
Full Idea: Plato and Aristotle have a shared general conception of essence: the essence of a thing is what that thing is simply in virtue of itself and in virtue of being the very thing it is. It answers the question 'What is this very thing?' | |
From: report of Plato (works [c.375 BCE]) by Vassilis Politis - Aristotle and the Metaphysics 1.4 |
22328 | I just confront the evidence, and let it act on me [Ramsey] |
Full Idea: I can but put the evidence before me, and let it act on my mind. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], p.202), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 70 'Deg' | |
A reaction: Potter calls this observation 'downbeat', but I am an enthusiastic fan. It is roughly my view of both concept formation and of knowledge. You soak up the world, and respond appropriately. The trick is in the selection of evidence to confront. |
22325 | A belief is knowledge if it is true, certain and obtained by a reliable process [Ramsey] |
Full Idea: I have always said that a belief was knowledge if it was 1) true, ii) certain, iii) obtained by a reliable process. | |
From: Frank P. Ramsey (The Foundations of Mathematics [1925], p.258), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 66 'Rel' | |
A reaction: Not sure why it has to be 'certain' as well as 'true'. It seems that 'true' is objective, and 'certain' subjective. I think I know lots of things of which I am not fully certain. Reliabilism long preceded Alvin Goldman. |
17085 | A good explanation totally rules out the opposite explanation (so Forms are required) [Plato, by Ruben] |
Full Idea: For Plato, an acceptable explanation is one such that there is no possibility of there being the opposite explanation at all, and he thought that only explanations in terms of the Forms, but never physical explanations, could meet this requirement. | |
From: report of Plato (works [c.375 BCE]) by David-Hillel Ruben - Explaining Explanation Ch 2 | |
A reaction: [Republic 436c is cited] |
1651 | Plato wanted to somehow control and purify the passions [Vlastos on Plato] |
Full Idea: Plato put high on his agenda a project which did not figure in Socrates' programme at all: the hygienic conditioning of the passions. This cannot be an intellectual process, as argument cannot touch them. | |
From: comment on Plato (works [c.375 BCE]) by Gregory Vlastos - Socrates: Ironist and Moral Philosopher p.88 | |
A reaction: This is the standard traditional view of any thinker who exaggerates the importance and potential of reason in our lives. |
3324 | Plato's whole philosophy may be based on being duped by reification - a figure of speech [Benardete,JA on Plato] |
Full Idea: Plato is liable to the charge of having been duped by a figure of speech, albeit the most profound of all, the trope of reification. | |
From: comment on Plato (works [c.375 BCE]) by José A. Benardete - Metaphysics: the logical approach Ch.12 | |
A reaction: That might be a plausible account if his view was ridiculous, but given how many powerful friends Plato has, especially in the philosophy of mathematics, we should assume he was cleverer than that. |
7503 | Plato never refers to examining the conscience [Plato, by Foucault] |
Full Idea: Plato never speaks of the examination of conscience - never! | |
From: report of Plato (works [c.375 BCE]) by Michel Foucault - On the Genealogy of Ethics p.276 | |
A reaction: Plato does imply some sort of self-evident direct knowledge about that nature of a healthy soul. Presumably the full-blown concept of conscience is something given from outside, from God. In 'Euthyphro', Plato asserts the primacy of morality (Idea 337). |
2173 | As religion and convention collapsed, Plato sought morals not just in knowledge, but in the soul [Williams,B on Plato] |
Full Idea: Once gods and fate and social expectation were no longer there, Plato felt it necessary to discover ethics inside human nature, not just as ethical knowledge (Socrates' view), but in the structure of the soul. | |
From: comment on Plato (works [c.375 BCE]) by Bernard Williams - Shame and Necessity II - p.43 | |
A reaction: anti Charles Taylor |
9274 | Plato's legacy to European thought was the Good, the Beautiful and the True [Plato, by Gray] |
Full Idea: Plato's legacy to European thought was a trio of capital letters - the Good, the Beautiful and the True. | |
From: report of Plato (works [c.375 BCE]) by John Gray - Straw Dogs 2.8 | |
A reaction: It seems to have been Baumgarten who turned this into a slogan (Idea 8117). Gray says these ideals are lethal, but I identify with them very strongly, and am quite happy to see the good life as an attempt to find the right balance between them. |
94 | Pleasure is better with the addition of intelligence, so pleasure is not the good [Plato, by Aristotle] |
Full Idea: Plato says the life of pleasure is more desirable with the addition of intelligence, and if the combination is better, pleasure is not the good. | |
From: report of Plato (works [c.375 BCE]) by Aristotle - Nicomachean Ethics 1172b27 | |
A reaction: It is obvious why we like pleasure, but not why intelligence makes it 'better'. Maybe it is just because we enjoy intelligence? |
17947 | Plato decided that the virtuous and happy life was the philosophical life [Plato, by Nehamas] |
Full Idea: Plato came to the conclusion that virtue and happiness consist in the life of philosophy itself. | |
From: report of Plato (works [c.375 BCE]) by Alexander Nehamas - Eristic,Antilogic,Sophistic,Dialectic p.117 | |
A reaction: This view is obviously ridiculous, because it largely excludes almost the entire human race, which sees philosophy as a cul-de-sac, even if it is good. But virtue and happiness need some serious thought. |
6015 | Plato, unusually, said that theoretical and practical wisdom are inseparable [Plato, by Kraut] |
Full Idea: Two virtues that are ordinarily kept distinct - theoretical and practical wisdom - are joined by Plato; he thinks that neither one can be fully possessed unless it is combined with the other. | |
From: report of Plato (works [c.375 BCE]) by Richard Kraut - Plato | |
A reaction: I get the impression that this doctrine comes from Socrates, whose position is widely reported as 'intellectualist'. Aristotle certainly held the opposite view. |
2912 | Plato is boring [Nietzsche on Plato] |
Full Idea: Plato is boring. | |
From: comment on Plato (works [c.375 BCE]) by Friedrich Nietzsche - Twilight of the Idols 9.2 |
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. |
1526 | Almost everyone except Plato thinks that time could not have been generated [Plato, by Aristotle] |
Full Idea: With a single exception (Plato) everyone agrees about time - that it is not generated. Democritus says time is an obvious example of something not generated. | |
From: report of Plato (works [c.375 BCE]) by Aristotle - Physics 251b14 |