Combining Texts

All the ideas for 'Necessary Existents', 'On the Question of Absolute Undecidability' and 'First Things First'

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11 ideas

4. Formal Logic / F. Set Theory ST / 1. Set Theory
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)
'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)
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
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)
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity
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]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
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.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic
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)
13. Knowledge Criteria / B. Internal Justification / 3. Evidentialism / b. Evidentialism
Evidentialism is not axiomatic; the evidence itself inclines us towards evidentialism [Conee]
     Full Idea: Evidentialism does not support beginning epistemology by taking for granted that evidentialism is true. ...Rather, what potentially justifies belief in intial epistemic data and initial procedures of inquiry is the evidence itself.
     From: Earl Conee (First Things First [2004], 'Getting')
     A reaction: This sounds good. I much prefer talk of 'evidence' to talk of 'perceptions', because evidence has been licked into shape, and its significance has been clarified. That is the first step towards the coherence we seek.
13. Knowledge Criteria / C. External Justification / 3. Reliabilism / b. Anti-reliabilism
If pure guesses were reliable, reliabilists would have to endorse them [Conee]
     Full Idea: Reliabilism would count pure guesses as good reasons if guessing were properly reliable.
     From: Earl Conee (First Things First [2004], 'Getting')
     A reaction: See D.H. Lawrence's short story 'The Rocking Horse Winner'. This objection strikes me as being so devastating that it is almost conclusive. Except that pure guesses are never ever reliable, over a decent period of time.
More than actual reliability is needed, since I may mistakenly doubt what is reliable [Conee]
     Full Idea: Sheer reliability does not justify belief. ...It may be, for instance, that we have strong though misleading reason to deny the method's reliability.
     From: Earl Conee (First Things First [2004], 'Circles')
     A reaction: That is, we accept a justification if we judge the method to be reliable, not if it IS reliable. I can disbelieve all the reliable information that arrives in my mind. People do that all the time! Hatred of experts! Support for internalism?
Reliabilism is poor on reflective judgements about hypothetical cases [Conee]
     Full Idea: An unrefined reliability theory does a poor job at capturing reflective judgements about hypothetical cases
     From: Earl Conee (First Things First [2004], 'Stroud's')
     A reaction: Reliability can only be a test for tried and tested ways. No one can say whether imagining a range of possibilities is reliable or not. Is prediction a reliable route to knowledge?
19. Language / D. Propositions / 3. Concrete Propositions
Propositions (such as 'that dog is barking') only exist if their items exist [Williamson]
     Full Idea: A proposition about an item exists only if that item exists... how could something be the proposition that that dog is barking in circumstances in which that dog does not exist?
     From: Timothy Williamson (Necessary Existents [2002], p.240), quoted by Trenton Merricks - Propositions
     A reaction: This is a view of propositions I can't make sense of. If I'm under an illusion that there is a dog barking nearby, when there isn't one, can I not say 'that dog is barking'? If I haven't expressed a proposition, what have I done?