16 ideas
192 | 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. |
6408 | Russell needed three extra axioms to reduce maths to logic: infinity, choice and reducibility [Grayling] |
Full Idea: In order to deduce the theorems of mathematics from purely logical axioms, Russell had to add three new axioms to those of standards logic, which were: the axiom of infinity, the axiom of choice, and the axiom of reducibility. | |
From: A.C. Grayling (Russell [1996], Ch.2) | |
A reaction: The third one was adopted to avoid his 'barber' paradox, but many thinkers do not accept it. The interesting question is why anyone would 'accept' or 'reject' an axiom. |
190 | 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) |
20185 | 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. |
20184 | 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. |
6414 | Two propositions might seem self-evident, but contradict one another [Grayling] |
Full Idea: Two propositions might contradict each other despite appearing self-evident when considered separately. | |
From: A.C. Grayling (Russell [1996], Ch.2) | |
A reaction: Russell's proposal (Idea 5416) is important here, that self-evidence comes in degrees. If self-evidence was all-or-nothing, Grayling's point would be a major problem, but it isn't. Bonjour explores the idea more fully (e.g. Idea 3704) |
12729 | The cause of a change is not the real influence, but whatever gives a reason for the change [Leibniz] |
Full Idea: That thing from whose state a reason for the changes is most readily provided is adjudged to be the cause. ...Causes are not derived from a real influence, but from the providing of a reason. | |
From: Gottfried Leibniz (Specimen inventorum [1689], A6.4.1620), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 5 | |
A reaction: Leibniz is not denying that there are real influences. He seems to be offering the thesis which I am pursuing, that the need for explanation is the crucial factor in shaping the structure of our metaphysics. |
191 | 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) |
203 | 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) |
202 | 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. |
193 | 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. |
197 | 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. |
200 | 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. |
188 | 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) |
204 | 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) |
189 | 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) |