15 ideas
| 343 | The unexamined life is not worth living for men [Socrates] |
| Full Idea: The unexamined life is not worth living for men. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 38a | |
| A reaction: I wonder why? I can see Nietzsche offering aristocratic heroes and dancers as counterexamples. Compare Idea 3798. |
| 17833 | The first-order ZF axiomatisation is highly non-categorical [Hallett,M] |
| Full Idea: The first-order Sermelo-Fraenkel axiomatisation is highly non-categorical. | |
| From: Michael Hallett (Introduction to Zermelo's 1930 paper [1996], p.1213) |
| 17834 | Non-categoricity reveals a sort of incompleteness, with sets existing that the axioms don't reveal [Hallett,M] |
| Full Idea: The non-categoricity of the axioms which Zermelo demonstrates reveals an incompleteness of a sort, ....for this seems to show that there will always be a set (indeed, an unending sequence) that the basic axioms are incapable of revealing to be sets. | |
| From: Michael Hallett (Introduction to Zermelo's 1930 paper [1996], p.1215) | |
| A reaction: Hallett says the incompleteness concerning Zermelo was the (transfinitely) indefinite iterability of the power set operation (which is what drives the 'iterative conception' of sets). |
| 17837 | Zermelo allows ur-elements, to enable the widespread application of set-theory [Hallett,M] |
| Full Idea: Unlike earlier writers (such as Fraenkel), Zermelo clearly allows that there might be ur-elements (that is, objects other than the empty set, which have no members). Indeed he sees in this the possibility of widespread application of set-theory. | |
| From: Michael Hallett (Introduction to Zermelo's 1930 paper [1996], p.1217) |
| 9390 | Logic guides thinking, but it isn't a substitute for it [Rumfitt] |
| Full Idea: Logic is part of a normative theory of thinking, not a substitute for thinking. | |
| From: Ian Rumfitt (The Logic of Boundaryless Concepts [2007], p.13) | |
| A reaction: There is some sort of logicians' dream, going back to Leibniz, of a reasoning engine, which accepts propositions and outputs inferences. I agree with this idea. People who excel at logic are often, it seems to me, modest at philosophy. |
| 17836 | The General Continuum Hypothesis and its negation are both consistent with ZF [Hallett,M] |
| Full Idea: In 1938, Gödel showed that ZF plus the General Continuum Hypothesis is consistent if ZF is. Cohen showed that ZF and not-GCH is also consistent if ZF is, which finally shows that neither GCH nor ¬GCH can be proved from ZF itself. | |
| From: Michael Hallett (Introduction to Zermelo's 1930 paper [1996], p.1217) |
| 9389 | Vague membership of sets is possible if the set is defined by its concept, not its members [Rumfitt] |
| Full Idea: Vagueness in respect of membership is consistency with determinacy of the set's identity, so long as a set's identity is taken to consist, not in its having such-and-such members, but in its being the extension of a concept. | |
| From: Ian Rumfitt (The Logic of Boundaryless Concepts [2007], p.5) | |
| A reaction: I find this view of sets much more appealing than the one that identifies a set with its members. The empty set is less of a problem, as well as non-existents. Logicians prefer the extensional view because it is tidy. |
| 339 | Men fear death as a great evil when it may be a great blessing [Socrates] |
| Full Idea: No one knows whether death may not be the greatest of all blessings for a man, yet men fear it as if they knew that it is the greatest of evils. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 29a | |
| A reaction: As a neutral observer, I see little sign of it being a blessing, except as a relief from misery. It seem wrong to view such a natural thing as evil, but it is the thing most of us least desire. |
| 344 | If death is like a night of dreamless sleep, such nights are very pleasant [Socrates] |
| Full Idea: If death is like a night of dreamless sleep it is an advantage, for such nights are very pleasant, and eternity would seem like a single night. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 40d | |
| A reaction: Dreamless sleep is only pleasant if being awake is unpleasant. Very quiet days are only pleasant if the active days are horrible. A desire for a totally quiet life is absurd. |
| 2 | We should not even harm someone who harms us [Socrates] |
| Full Idea: One should never return an injustice nor harm another human being no matter what one suffers at their hands. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - Crito 49c | |
| A reaction: Jesus of Nazareth was not the first person to make this suggestion. |
| 345 | A good man cannot be harmed, either in life or in death [Socrates] |
| Full Idea: A good man cannot be harmed, either in life or in death. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 41d |
| 346 | One ought not to return a wrong or injury to any person, whatever the provocation [Socrates] |
| Full Idea: One ought not to return a wrong or an injury to any person, whatever the provocation is. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - Crito 49b | |
| A reaction: The same as the essential moral teachings of Jesus (see Idea 6288) and Lao Tzu (Idea 6324). The big target is not to be corrupted by the evil of other people. |
| 341 | Wealth is good if it is accompanied by virtue [Socrates] |
| Full Idea: Wealth does not bring about excellence, but excellence makes wealth and everything else good for men. | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - The Apology 30b |
| 347 | Will I stand up against the law, simply because I have been unjustly judged? [Socrates] |
| Full Idea: Do I intend to destroy the laws, because the state wronged me by passing a faulty judgement at my trial? | |
| From: Socrates (reports of last days [c.399 BCE]), quoted by Plato - Crito 50c |
| 338 | Socrates is accused of denying the gods, saying sun is stone and moon is earth [Socrates, by Plato] |
| Full Idea: Socrates denies the gods, because he says the sun is stone and the moon is earth. | |
| From: report of Socrates (reports of last days [c.399 BCE]) by Plato - The Apology 26d |