Combining Texts

All the ideas for 'Protagoras', 'works' and 'On the True Doctrine (Against Christians)'

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19 ideas

2. Reason / B. Laws of Thought / 4. Contraries
Only one thing can be contrary to something [Plato]
     Full Idea: To everything that admits of a contrary there is one contrary and no more.
     From: Plato (Protagoras [c.380 BCE], 332c)
     A reaction: The sort of thing for which a modern philosopher would demand a proof (and then reject when the proof couldn't be found), where a Greek is happy to assert it as self-evident. I can't think of a counterexample.
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
Hilbert wanted to prove the consistency of all of mathematics (which realists take for granted) [Hilbert, by Friend]
     Full Idea: Hilbert wanted to derive ideal mathematics from the secure, paradox-free, finite mathematics (known as 'Hilbert's Programme'). ...Note that for the realist consistency is not something we need to prove; it is a precondition of thought.
     From: report of David Hilbert (works [1900], 6.7) by Michčle Friend - Introducing the Philosophy of Mathematics
     A reaction: I am an intuitive realist, though I am not so sure about that on cautious reflection. Compare the claims that there are reasons or causes for everything. Reality cannot contain contradicitions (can it?). Contradictions would be our fault.
6. Mathematics / C. Sources of Mathematics / 7. Formalism
The grounding of mathematics is 'in the beginning was the sign' [Hilbert]
     Full Idea: The solid philosophical attitude that I think is required for the grounding of pure mathematics is this: In the beginning was the sign.
     From: David Hilbert (works [1900]), quoted by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6
     A reaction: Why did people invent those particular signs? Presumably they were meant to designate something, in the world or in our experience.
Hilbert substituted a syntactic for a semantic account of consistency [Hilbert, by George/Velleman]
     Full Idea: Hilbert replaced a semantic construal of inconsistency (that the theory entails a statement that is necessarily false) by a syntactic one (that the theory formally derives the statement (0 =1 ∧ 0 not-= 1).
     From: report of David Hilbert (works [1900]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6
     A reaction: Finding one particular clash will pinpoint the notion of inconsistency, but it doesn't seem to define what it means, since the concept has very wide application.
6. Mathematics / C. Sources of Mathematics / 8. Finitism
Hilbert aimed to prove the consistency of mathematics finitely, to show infinities won't produce contradictions [Hilbert, by George/Velleman]
     Full Idea: Hilbert's project was to establish the consistency of classical mathematics using just finitary means, to convince all parties that no contradictions will follow from employing the infinitary notions and reasoning.
     From: report of David Hilbert (works [1900]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6
     A reaction: This is the project which was badly torpedoed by Gödel's Second Incompleteness Theorem.
8. Modes of Existence / D. Universals / 6. Platonic Forms / c. Self-predication
If asked whether justice itself is just or unjust, you would have to say that it is just [Plato]
     Full Idea: If someone asked me 'Is justice itself just or unjust?' I should answer that it was just, wouldn't you? I agree.
     From: Plato (Protagoras [c.380 BCE], 330c)
11. Knowledge Aims / A. Knowledge / 3. Value of Knowledge
The only real evil is loss of knowledge [Plato]
     Full Idea: The only real kind of faring ill is the loss of knowledge.
     From: Plato (Protagoras [c.380 BCE], 345b)
     A reaction: This must crucially involve the intellectualist view (of Socrates) that virtuos behaviour results from knowledge, and moral wickedness is the result of ignorance. It is hard to see how forgetting a phone number is evil.
The most important things in life are wisdom and knowledge [Plato]
     Full Idea: It would be shameful indeed to say that wisdom and knowledge are anything but the most powerful forces in human activity.
     From: Plato (Protagoras [c.380 BCE], 352d)
     A reaction: He lumps wisdom and knowledge together, and I think we can take 'knowledge' to mean something like understanding, because obviously mere atomistic propositional knowledge can be utterly trivial.
15. Nature of Minds / C. Capacities of Minds / 7. Seeing Resemblance
Everything resembles everything else up to a point [Plato]
     Full Idea: Everything resembles everything else up to a point.
     From: Plato (Protagoras [c.380 BCE], 331d)
20. Action / C. Motives for Action / 3. Acting on Reason / b. Intellectualism
Courage is knowing what should or shouldn't be feared [Plato]
     Full Idea: Knowledge of what is and is not to be feared is courage.
     From: Plato (Protagoras [c.380 BCE], 360d)
22. Metaethics / B. Value / 2. Values / j. Evil
No one willingly and knowingly embraces evil [Plato]
     Full Idea: No one willingly goes to meet evil, or what he thinks is evil.
     From: Plato (Protagoras [c.380 BCE], 358d)
     A reaction: Presumably people who actively choose satanism can override this deep-seated attitude. But their adherence to evil usually seems to be rather restrained. A danger of tautology with ideas like this.
22. Metaethics / C. The Good / 1. Goodness / h. Good as benefit
Some things are good even though they are not beneficial to men [Plato]
     Full Idea: 'Do you mean by good those things that are beneficial to men?' 'Not only those. I call some things which are not beneficial good as well'.
     From: Plato (Protagoras [c.380 BCE], 333e)
     A reaction: Examples needed, but this would be bad news for utilitarians. Good health is not seen as beneficial if it is taken for granted. Not being deaf.
22. Metaethics / C. The Good / 3. Pleasure / c. Value of pleasure
Some pleasures are not good, and some pains are not evil [Plato]
     Full Idea: There are some pleasures which are not good, and some pains which are not evil.
     From: Plato (Protagoras [c.380 BCE], 351d)
     A reaction: Sadism and child birth. Though Bentham (I think) says that there is nothing good about the pain, since the event would obviously be better without it.
People tend only to disapprove of pleasure if it leads to pain, or prevents future pleasure [Plato]
     Full Idea: The only reason the common man disapproves of pleasures is if they lead to pain and deprive us of future pleasures.
     From: Plato (Protagoras [c.380 BCE], 354a)
     A reaction: Plato has a strong sense that some pleasures are just innately depraved and wicked. If those pleasure don't hurt anyone, it is very hard to pinpoint what is wrong with them.
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / d. Teaching virtue
If we punish wrong-doers, it shows that we believe virtue can be taught [Plato]
     Full Idea: Athenians inflict punishment on wrong-doers, which shows that they too think it possible to impart and teach goodness.
     From: Plato (Protagoras [c.380 BCE], 324c)
Socrates did not believe that virtue could be taught [Plato]
     Full Idea: Socrates: I do not believe that virtue can be taught.
     From: Plato (Protagoras [c.380 BCE], 320b)
Socrates is contradicting himself in claiming virtue can't be taught, but that it is knowledge [Plato]
     Full Idea: Socrates is contradicting himself by saying virtue is not teachable, and yet trying to demonstrate that every virtue is knowledge.
     From: Plato (Protagoras [c.380 BCE], 361b)
25. Social Practice / F. Life Issues / 6. Animal Rights
The world was made as much for animals as for man [Celsus]
     Full Idea: The world was made as much for the irrational animals as for men.
     From: Celsus (On the True Doctrine (Against Christians) [c.178], §V)
     A reaction: A good remark. It seems to be a classic distortion of European Christianity that the world is made for us, and that animals only exist to fill our sandwiches.
29. Religion / B. Monotheistic Religion / 4. Christianity / a. Christianity
Christians presented Jesus as a new kind of logos to oppose that of the philosophers [Celsus]
     Full Idea: Christians put forth this Jesus not only as the son of God, but as the very Logos - not the pure and holy Logos known to the philosophers, but a new kind of Logos.
     From: Celsus (On the True Doctrine (Against Christians) [c.178], III)