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) |
| 21432 | Culture is the struggle to agree what is normal [Gibson,A] |
| Full Idea: Culture is the struggle to agree what is normal. | |
| From: Andrew Gibson (talk [2018]) | |
| A reaction: A nice aphorism. Typically the struggle took place in villages, but has now gone global. The normalities of other cultures are beamed into a remote society, and are frequently unwelcome. |
| 21798 | To universalise 'give everything to the poor' leads to absurdity [Hegel] |
| Full Idea: If everyone gave everything to the poor, then soon there would be no more poor to give anything to, or no more persons who would have anything to give. | |
| From: Georg W.F.Hegel (Lectures on the Philosophy of Religion [1827], III: 152), quoted by Stephen Houlgate - An Introduction to Hegel 10 'Faith' | |
| A reaction: Matthew 5:8, 19:21. Beautifully clear. [I always believed that I had thought of this idea - but not so]. If the logic is that it is better to be poor than to be rich, then the implication is that all excess wealth should be thrown into the sea. |
| 21797 | Immortality does not come at a later time, but when pure knowing Spirit fully grasps the universal [Hegel] |
| Full Idea: The immortality of the soul must not be imagined as though it first emerges into actuality at some later time; rather it is a present quality. ...As pure knowing or as thinking, Spirit has the universal for its object - this is eternity. | |
| From: Georg W.F.Hegel (Lectures on the Philosophy of Religion [1827], III: 208), quoted by Stephen Houlgate - An Introduction to Hegel 10 'Death' | |
| A reaction: An unusual view of immortality, which challenges orthodoxy. The idea seems to be that 'pure knowing' is a grasping of the pure reason which embodies nature, which in turn is the nature of God. You enter eternity, rather than reside in it? |