17 ideas
| 17884 | Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner] |
| Full Idea: There are many coherent stopping points in the hierarchy of increasingly strong mathematical systems, starting with strict finitism, and moving up through predicativism to the higher reaches of set theory. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], Intro) |
| 17893 | 'Reflection principles' say the whole truth about sets can't be captured [Koellner] |
| Full Idea: Roughly speaking, 'reflection principles' assert that anything true in V [the set hierarchy] falls short of characterising V in that it is true within some earlier level. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 2.1) |
| 17894 | We have no argument to show a statement is absolutely undecidable [Koellner] |
| Full Idea: There is at present no solid argument to the effect that a given statement is absolutely undecidable. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 5.3) |
| 17890 | There are at least eleven types of large cardinal, of increasing logical strength [Koellner] |
| Full Idea: Some of the standard large cardinals (in order of increasing (logical) strength) are: inaccessible, Mahlo, weakly compact, indescribable, Erdös, measurable, strong, Wodin, supercompact, huge etc. (...and ineffable). | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) | |
| A reaction: [I don't understand how cardinals can have 'logical strength', but I pass it on anyway] |
| 17887 | PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner] |
| Full Idea: To the extent that we are justified in accepting Peano Arithmetic we are justified in accepting its consistency, and so we know how to expand the axiom system so as to overcome the limitation [of Gödel's Second Theorem]. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.1) | |
| A reaction: Each expansion brings a limitation, but then you can expand again. |
| 17891 | Arithmetical undecidability is always settled at the next stage up [Koellner] |
| Full Idea: The arithmetical instances of undecidability that arise at one stage of the hierarchy are settled at the next. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) |
| 22142 | In future, only logical limits can be placed on divine omnipotence [Anon (Par), by Boulter] |
| Full Idea: The Condemnation stipulated that all portions of the ancient intellectual heritage that placed non-logical limits on divine omnipotence were no longer to be tolerated. ...Philosophers now had to entertain the wildest ideas with all seriousness. | |
| From: report of Anon (Par) (The Condemnation of 1277 [1277]) by Stephen Boulter - Why Medieval Philosophy Matters 3 | |
| A reaction: Boulter identifies this as 'the ultimate source of Hume's philosophical delirium'. Presumably the angels-on-a-pinhead stuff originated with this. It is crazy to think that the only limit on possible existence is logic. Can God make a planet of uranium? |
| 16716 | It is heresy to require self-evident foundational principles in order to be certain [Anon (Par)] |
| Full Idea: Heresy 151: 'To have certainty regarding any conclusion, it must be founded on self-evident principles'. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], 151), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 20.3 | |
| A reaction: The correct view is obviously to found certainty on faith and authority. It is one thing to be told that foundationalism is a poor theory, but another to be told it is a heresy, and thus a potential capital crime! |
| 8353 | Freedom involves acting according to an idea [Anscombe] |
| Full Idea: Freedom at least involves the power of acting according to an idea. | |
| From: G.E.M. Anscombe (Causality and Determinism [1971], §2) | |
| A reaction: Since 'you' presumably have to sit above the idea and pass a judgement on it, then the same principle should apply to acting on a desire, which presumably 'you' could reject because it just wasn't attractive enough. |
| 8352 | To believe in determinism, one must believe in a system which determines events [Anscombe] |
| Full Idea: 'The ball's path is determined' must mean 'there is only one possible path for the ball (assuming no air currents)', but what ground could one have for believing this, if one does not believe in some system for which it is a consequence? | |
| From: G.E.M. Anscombe (Causality and Determinism [1971], §2) | |
| A reaction: This seems right, but it doesn't follow that one has to know the full details of the system. The system might just be the best explanation, or even a matter of vague faith. It might, though, be just that you can't imagine any other outcome. |
| 1866 | It is heresy to teach that history repeats every 36,000 years [Anon (Par)] |
| Full Idea: It is heresy to teach that with all the heavenly bodies coming back to the same point after a period of thirty-six thousand years, the same effects as now exist will reappear. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], §92) |
| 8351 | With diseases we easily trace a cause from an effect, but we cannot predict effects [Anscombe] |
| Full Idea: It is much easier to trace effects back to causes with certainty than to predict effects from causes. If I have one contact with someone with a disease and I get it, we suppose I got it from him, but a doctor cannot predict a disease from one contact. | |
| From: G.E.M. Anscombe (Causality and Determinism [1971], §1) | |
| A reaction: An interesting, and obviously correct, observation. Her point is that we get more certainty of causes from observing a singular effect than we get certainty of effects from regularities or laws. |
| 4777 | The word 'cause' is an abstraction from a group of causal terms in a language (scrape, push..) [Anscombe] |
| Full Idea: The word "cause" can be added to a language in which are already represented many causal concepts; a small selection: scrape, push, wet, carry, eat, burn, knock over, keep off, squash, make, hurt. | |
| From: G.E.M. Anscombe (Causality and Determinism [1971], p.93) | |
| A reaction: An interesting point, perhaps reinforcing the Humean idea of causation as a 'natural belief', or the Kantian view of it as a category of thought. Or maybe causation is built into language because it is a feature of reality… |
| 10363 | Causation is relative to how we describe the primary relata [Anscombe, by Schaffer,J] |
| Full Idea: Anscombe has inspired the view that causation is an intensional relation, and takes it to be relative to the descriptions of the primary relata. | |
| From: report of G.E.M. Anscombe (Causality and Determinism [1971], 1) by Jonathan Schaffer - The Metaphysics of Causation 1 | |
| A reaction: It seems too linguistic to say that there is nothing more to it. It seems relevant in human examples, but if a landslide crushes a tree, what difference does the description make? 'It was just a few rocks and some miserable little tree'. No excuse! |
| 8350 | Since Mill causation has usually been explained by necessary and sufficient conditions [Anscombe] |
| Full Idea: Since Mill it has been fairly common to explain causation one way or another in terms of 'necessary' and 'sufficient' conditions. | |
| From: G.E.M. Anscombe (Causality and Determinism [1971], §1) | |
| A reaction: Interesting to see what Hume implies about these criteria. Anscombe is going to propose that causal events are fairly self-evident and self-explanatory, and don't need analyses of conditions. Another approach is regularities and laws. |
| 1865 | It is heresy to teach that natural impossibilities cannot even be achieved by God [Anon (Par)] |
| Full Idea: It is heresy to teach that what is absolutely impossible according to nature cannot be brought about by God or another agent. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], §17) |
| 1864 | It is heresy to teach that we can know God by his essence in this mortal life [Anon (Par)] |
| Full Idea: It is heresy to teach that we can know God by his essence in this mortal life. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], §9) |