11 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) |
| 3291 | Emergent properties appear at high levels of complexity, but aren't explainable by the lower levels [Nagel] |
| Full Idea: The supposition that a diamond or organism should truly have emergent properties is that they appear at certain complex levels of organisation, but are not explainable (even in principle) in terms of any more fundamental properties of the system. | |
| From: Thomas Nagel (Panpsychism [1979], p.186) |
| 19555 | People begin to doubt whether they 'know' when the answer becomes more significant [Conee] |
| Full Idea: Fluent speakers typically become increasingly hesitant about 'knowledge' attributions as the practical significance of the right answer increases. | |
| From: Earl Conee (Contextualism Contested (and reply) [2005], 'Epistemic') | |
| A reaction: The standard examples of this phenomenon are in criminal investigations, and in philosophical discussions of scepticism. Simple observations I take to have maximum unshakable confidence, except in extreme global scepticism contexts. |
| 19557 | Maybe low knowledge standards are loose talk; people will deny that it is 'really and truly' knowledge [Conee] |
| Full Idea: Maybe variable knowledge ascriptions are just loose talk. This is shown when we ask whether weakly supported knowledge is 'really' or 'truly' or 'really and truly' known. Fluent speakers have a strong inclination to doubt or deny that it is. | |
| From: Earl Conee (Contextualism Contested (and reply) [2005], 'Loose') | |
| A reaction: [bit compressed] Conee is suggesting the people are tacitly invariantist about knowledge (they have a fixed standard). But it may be that someone who asks 'do you really and truly know?' is raising the contextual standard. E.g. a barrister. |
| 19556 | Maybe knowledge has fixed standards (high, but attainable), although people apply contextual standards [Conee] |
| Full Idea: It may be that all 'knowledge' attributions have the same truth conditions, but people apply contextually varying standards. The most plausible standard for truth is very high, but not unreachably high. | |
| From: Earl Conee (Contextualism Contested (and reply) [2005], 'Loose') | |
| A reaction: This is the 'invariantist' alternative to contextualism about knowledge. Is it a standard 'for truth'? Either it is or it isn't true, so there isn't a standard. I take the standard to concern the justification. |
| 3290 | Given the nature of heat and of water, it is literally impossible for water not to boil at the right heat [Nagel] |
| Full Idea: Given what heat is and what water is, it is literally impossible for water to be heated beyond a certain point at normal atmospheric pressure without boiling. | |
| From: Thomas Nagel (Panpsychism [1979], p.186) |