9 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) |
18521 | The criterion of existence is the possibility of action [Santayana] |
Full Idea: The possibility of action ...is the criterion of existence, and the test of substantiality. | |
From: George Santayana (The Realm of Matter [1930], p.107), quoted by John Heil - The Universe as We Find It | |
A reaction: I rather like this. I think I would say the power is the criterion of existence. |
22040 | Freedom is produced by the activity of the mind, and is not intrinsically given [Hegel] |
Full Idea: Actual freedom is not something immediately existent in mindedness, but is something to be produced by the mind's own activity. It is thus as the producer of its freedom that we have to consider mindedness in philosophy. | |
From: Georg W.F.Hegel (Philosophy of Mind (Encylopedia III) [1817], §382, Zusatz), quoted by Terry Pinkard - German Philosophy 1760-1860 11 | |
A reaction: Pinkard glosses this as an agent being free by being the centre of a group of social responsibilities. Hence I presume small children have no freedom. Presumably we could deprive citizens of all responsibility, and hence of metaphysical freedom. |
22039 | Geist is distinct from nature, not as a substance, but because of its normativity [Hegel, by Pinkard] |
Full Idea: Hegel argued that it was the impossibility of a naturalistic account of normativity that distinguished Geist from nature, not Geist's being any kind of metaphysical substance. | |
From: report of Georg W.F.Hegel (Philosophy of Mind (Encylopedia III) [1817]) by Terry Pinkard - German Philosophy 1760-1860 11 | |
A reaction: Hegel always seems to want to have his cake and eat it. Without a mental substance, how can Geist not be part of nature? What is Geist made of? Is his view functionalist? But that is usually naturalistic. Is normativity magic? |