10 ideas
| 23367 | Even pointing a finger should only be done for a reason [Epictetus] |
| Full Idea: Philosophy says it is not right even to stretch out a finger without some reason. | |
| From: Epictetus (fragments/reports [c.57], 15) | |
| A reaction: The key point here is that philosophy concerns action, an idea on which Epictetus is very keen. He rather despise theory. This idea perfectly sums up the concept of the wholly rational life (which no rational person would actually want to live!). |
| 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) |
| 12314 | Audience-relative explanation, or metaphysical explanation based on information? [Stanford] |
| Full Idea: Rather than an 'interest-relative' notion of explanation (Putnam), it can be informational content which makes an explanation, which is an 'audience-invariant' contraint, which is not pragmatic, but mainly epistemological and also partly metaphysical. | |
| From: Michael Stanford (Explanation: the state of play [1991], p.172) | |
| A reaction: [compressed summary of Ruben 1990] Examples given are that Rome burning explains Nero fiddling, even if no one ever says so, and learning that George III had porphyria explains his madness. |
| 12313 | Explanation is for curiosity, control, understanding, to make meaningful, or to give authority [Stanford] |
| Full Idea: There are a number of reasons why we explain: out of sheer curiosity, to increase our control of a situation, to help understanding by simplifying or making familiar, to confer meaning or significance, and to give scientific authority to some statement. | |
| From: Michael Stanford (Explanation: the state of play [1991], p.172) |
| 12315 | We can explain by showing constitution, as well as showing causes [Stanford] |
| Full Idea: The powerful engine of my car can be explained by an examination of each of its parts, but it is not caused by them. They do not cause the engine; they constitute it. | |
| From: Michael Stanford (Explanation: the state of play [1991], p.174) | |
| A reaction: [example from Ruben 1990:221] This could be challenged, since there is clearly a causal connection between the constitution and the whole. We distinguish engine parts which contribute to the power from those which do not. |