7 ideas
10196 | The Axiom of Choice needs a criterion of choice [Black] |
Full Idea: Some mathematicians seem to think that talk of an Axiom of Choice allows them to choose a single member of a collection when there is no criterion of choice. | |
From: Max Black (The Identity of Indiscernibles [1952], p.68) |
10194 | Two things can only be distinguished by a distinct property or a distinct relation [Black] |
Full Idea: The only way we can discover that two things exist is by finding out that one has a quality not possessed by the other, or else that one has a relational characteristic that the other hasn't. | |
From: Max Black (The Identity of Indiscernibles [1952], p.67) | |
A reaction: At least this doesn't conflate relations with properties. Note that this idea is clearly epistemological, and in no way rules out the separateness of two objects which none of us can ever discern. Maybe the Earth has two Suns, which imperceptibly swap. |
10193 | The 'property' of self-identity is uselessly tautological [Black] |
Full Idea: Saying that 'a has the property of being identical with a' is a roundabout way of saying nothing - a useless tautology - and means not more than 'a is a' | |
From: Max Black (The Identity of Indiscernibles [1952], p.66) | |
A reaction: This matter resembles the problem of the number zero, and the empty set, which seem to be crucial entities for logicians, but of no interest to a common sense view of the world. So much the worse for logic, I am inclined to say. |
10195 | If the universe just held two indiscernibles spheres, that refutes the Identity of Indiscernibles [Black] |
Full Idea: Isn't it logically possible that the universe should have contained nothing but two exactly similar spheres? ...So two things would have all their properties in common, and this would refute the Principle of the Identity of Indiscernibles. | |
From: Max Black (The Identity of Indiscernibles [1952], p.67) | |
A reaction: [Black is the originator of this famous example] It also appears to be naturally possible. An observer at an instant of viewing will discern a relational difference relative to themselves. Most people take Black's objection to be decisive. |
20618 | Persons must be conscious, reasoning, motivated, communicative, self-aware [Warren, by Tuckness/Wolf] |
Full Idea: Suggested characteristics of personhood: consciousness (esp. of pain); reasoning and problem solving; self-motivated activity; varied communication on many topics; self-concepts and self-awareness. | |
From: report of Mary Anne Warren (On the Moral and Legal State of Abortion [1973], p.55) by Tuckness,A/Wolf,C - This is Political Philosophy 8 'Standing' | |
A reaction: [a 'famous' article] A number of non-human animals come very close to passing these tests. I suspect the complex communication is only in there to disqualify them from getting the full certificate. (But she wrote on animal rights). |
13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
Full Idea: In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes. | |
From: Posidonius (fragments/reports [c.95 BCE]), quoted by Seneca the Younger - Letters from a Stoic 078 | |
A reaction: These remarks endorsing the infinite superiority of the educated to the uneducated seem to have been popular in late antiquity. It tends to be the religions which discourage great learning, especially in their emphasis on a single book. |
20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness. | |
From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42 | |
A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them. |