3 ideas
| 8920 | Equivalence relations are reflexive, symmetric and transitive, and classify similar objects [Lipschutz] |
| Full Idea: A relation R on a non-empty set S is an equivalence relation if it is reflexive (for each member a, aRa), symmetric (if aRb, then bRa), and transitive (aRb and bRc, so aRc). It tries to classify objects that are in some way 'alike'. | |
| From: Seymour Lipschutz (Set Theory and related topics (2nd ed) [1998], 3.9) | |
| A reaction: So this is an attempt to formalise the common sense notion of seeing that two things have something in common. Presumably a 'way' of being alike is going to be a property or a part |
| 23137 | Liberty without socialism is injustice; socialism without liberty is brutality [Bakunin] |
| Full Idea: Liberty without socialism is injustice; socialism without liberty is slavery and brutality. | |
| From: Mikhail Bakunin (works [1867], 3), quoted by Adam Gopnik - A Thousand Small Sanities 3 | |
| A reaction: [1867, but no reference] Bakunin was an anarchistic socialist. This must be the best one-line defence of socialism ever written. Gopnik quotes it as part of the anarchist critique of liberalism. So are liberty and socialism long-term compatible? |
| 1513 | The Egyptians were the first to say the soul is immortal and reincarnated [Herodotus] |
| Full Idea: The Egyptians were the first to claim that the soul of a human being is immortal, and that each time the body dies the soul enters another creature just as it is being born. | |
| From: Herodotus (The Histories [c.435 BCE], 2.123.2) |