5 ideas
| 18758 | Validity is provable, but invalidity isn't, because the model is infinite [Church, by McGee] |
| Full Idea: Church showed that logic has a proof procedure, but no decision procedure. If an argument is invalid, there is a model with true premises and false conclusion, but the model will typically be infinite, so there is no way to display it concretely. | |
| From: report of Alonzo Church (A Note on the entscheidungsproblem [1936]) by Vann McGee - Logical Consequence 5 |
| 22593 | Our sensation of light may not be the same as what produces the sensation [Descartes] |
| Full Idea: There can be a difference between our sensation of light and what is in the objects that produce that sensation in us. | |
| From: René Descartes (The World [1631]), quoted by Ian Dunt - How to be a Liberal 1 | |
| A reaction: Note only that they 'may' differ, and that he does not assert that they are entirely different. Secondary qualities give information, and are not just mental events. |
| 6017 | Nomos is king [Pindar] |
| Full Idea: Nomos is king. | |
| From: Pindar (poems [c.478 BCE], S 169), quoted by Thomas Nagel - The Philosophical Culture | |
| A reaction: This seems to be the earliest recorded shot in the nomos-physis wars (the debate among sophists about moral relativism). It sounds as if it carries the full relativist burden - that all that matters is what has been locally decreed. |
| 16569 | The Hot, Cold, Wet and Dry of the philosophers need themselves to be explained [Descartes] |
| Full Idea: If you find it strange that in explaining these elements I do not use the qualities called Hot, Cold, Wet and Dry - as the philosophers do - I shall say to you that these qualities themselves seem to me to need explanation. | |
| From: René Descartes (The World [1631], 9:25-6), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 1.3 | |
| A reaction: Nice. I take pushing the boundaries of explanation back (or down) to be the basic driving force of all human thought, in metaphysics as well as in physics. |
| 20964 | Descartes said there was conservation of 'quantity of motion' [Descartes, by Papineau] |
| Full Idea: Descartes incorporated the conservation of what he called 'quantity of motion', by which he meant mass times speed. | |
| From: report of René Descartes (The World [1631]) by David Papineau - Thinking about Consciousness App 2 | |
| A reaction: Mass times velocity is now called 'momentum'. Is this the first ever conservation law? There are now lots of them. |