12 ideas
| 5035 | The two basics of reasoning are contradiction and sufficient reason [Leibniz] |
| 5163 | Basic propositions refer to a single experience, are incorrigible, and conclusively verifiable [Ayer] |
| 5167 | The argument from analogy fails, so the best account of other minds is behaviouristic [Ayer] |
| 5038 | Assume that mind and body follow their own laws, but God has harmonised them [Leibniz] |
| 5164 | A statement is meaningful if observation statements can be deduced from it [Ayer] |
| 5165 | Directly verifiable statements must entail at least one new observation statement [Ayer] |
| 5166 | The principle of verification is not an empirical hypothesis, but a definition [Ayer] |
| 5162 | Sentences only express propositions if they are meaningful; otherwise they are 'statements' [Ayer] |
| 5168 | Moral approval and disapproval concerns classes of actions, rather than particular actions [Ayer] |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| 5037 | God doesn't decide that Adam will sin, but that sinful Adam's existence is to be preferred [Leibniz] |