6 ideas
| 18085 | Values that approach zero, becoming less than any quantity, are 'infinitesimals' [Cauchy] |
| Full Idea: When the successive absolute values of a variable decrease indefinitely in such a way as to become less than any given quantity, that variable becomes what is called an 'infinitesimal'. Such a variable has zero as its limit. | |
| From: Augustin-Louis Cauchy (Cours d'Analyse [1821], p.19), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.4 | |
| A reaction: The creator of the important idea of the limit still talked in terms of infinitesimals. In the next generation the limit took over completely. |
| 18084 | When successive variable values approach a fixed value, that is its 'limit' [Cauchy] |
| Full Idea: When the values successively attributed to the same variable approach indefinitely a fixed value, eventually differing from it by as little as one could wish, that fixed value is called the 'limit' of all the others. | |
| From: Augustin-Louis Cauchy (Cours d'Analyse [1821], p.19), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.4 | |
| A reaction: This seems to be a highly significan proposal, because you can now treat that limit as a number, and adds things to it. It opens the door to Cantor's infinities. Is the 'limit' just a fiction? |
| 21710 | We know a universal in 'yellow differs from blue' or 'yellow resembles blue less than green does' [Russell] |
| Full Idea: We are aware of the universal 'yellow'; this universal is the subject in such judgements as 'yellow differs from blue' or 'yellow resembles blue less than green does'. | |
| From: Bertrand Russell (Knowledge by Acquaintance and Description-1 [1911], 154), quoted by Bernard Linsky - Russell's Metaphysical Logic 2.3 | |
| A reaction: This still seems one of the strongest examples in support of universals. You could hardly be talking about yellow tropes in such instances (even if the world does contain yellow tropes). |
| 8854 | My 'acquaintance' with sense-data is nothing like my knowing New York [Williams,M on Russell] |
| Full Idea: My 'acquaintance' with sense-data is nothing like my knowing New York. | |
| From: comment on Bertrand Russell (Knowledge by Acquaintance and Description-1 [1911]) by Michael Williams - Without Immediate Justification §4 | |
| A reaction: This pinpoints a nice difficulty for Russell. Williams may misrepresent Russell's account of acquaintance, but that is probably because Russell is unclear, or uncertain. The problem is when Russell claims that his acquaintance gives knowledge. |
| 16713 | Philosophers are the forefathers of heretics [Tertullian] |
| Full Idea: Philosophers are the forefathers of heretics. | |
| From: Tertullian (works [c.200]), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 20.2 |
| 6610 | I believe because it is absurd [Tertullian] |
| Full Idea: I believe because it is absurd ('Credo quia absurdum est'). | |
| From: Tertullian (works [c.200]), quoted by Robert Fogelin - Walking the Tightrope of Reason n4.2 | |
| A reaction: This seems to be a rather desperate remark, in response to what must have been rather good hostile arguments. No one would abandon the support of reason if it was easy to acquire. You can't deny its engaging romantic defiance, though. |