13 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) |
| 14620 | Theories in logic are sentences closed under consequence, but in truth discussions theories have axioms [Fine,K] |
| Full Idea: It is customary in logic to take a theory to be a set of sentences closed under logical consequence, whereas it is common in discussions of theories of truth to take a theory to be an axiomatized theory. | |
| From: Kit Fine (Semantic Necessity [2010], n8) |
| 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) |
| 14665 | We can call the quality of Plato 'Platonity', and say it is a quality which only he possesses [Boethius] |
| Full Idea: Let the incommunicable property of Plato be called 'Platonity'. For we can call this quality 'Platonity' by a fabricated word, in the way in which we call the quality of man 'humanity'. Therefore this Platonity is one man's alone - Plato's. | |
| From: Boethius (Librium de interpretatione editio secunda [c.516], PL64 462d), quoted by Alvin Plantinga - Actualism and Possible Worlds 5 | |
| A reaction: Plantinga uses this idea to reinstate the old notion of a haecceity, to bestow unshakable identity on things. My interest in the quotation is that the most shocking confusions about properties arose long before the invention of set theory. |
| 14530 | The role of semantic necessity in semantics is like metaphysical necessity in metaphysics [Fine,K, by Hale/Hoffmann,A] |
| Full Idea: Fine's paper argues that the notion of semantic necessity has a role to play in understanding the nature and content of semantics comparable to the role of metaphysical necessity in metaphysics. | |
| From: report of Kit Fine (Semantic Necessity [2010]) by Bob Hale/ Aviv Hoffmann - Introduction to 'Modality' 2 |
| 14618 | Semantics is either an assignment of semantic values, or a theory of truth [Fine,K] |
| Full Idea: On one view, a semantics for a given language is taken to be an assignment of semantic values to its expressions; according to the other, a semantics is taken to be a theory of truth for that language. | |
| From: Kit Fine (Semantic Necessity [2010], Intro) | |
| A reaction: The first is Frege, the second Tarski via Davidson, says Fine. Fine argues against these as the correct alternatives, and says the distinction prevents us understanding what is really going on. He votes for semantics as giving 'semantic requirements'. |
| 14621 | Semantics is a body of semantic requirements, not semantic truths or assigned values [Fine,K] |
| Full Idea: Semantics should be conceived as a body of semantic requirements or facts - and not as a body of semantic truths, or as an assignment of semantic values. | |
| From: Kit Fine (Semantic Necessity [2010], 5) | |
| A reaction: The 'truths' view is Tarski, and the 'values' view is Frege. You'll have to read the Fine paper to grasp his subtle claim. |
| 14622 | Referential semantics (unlike Fregeanism) allows objects themselves in to semantic requirements [Fine,K] |
| Full Idea: What distinguishes the referential position in semantics from Fregeanism is that it makes use of de re semantic facts, in which it is required of an object itself that it enter into certain semantic requirements. | |
| From: Kit Fine (Semantic Necessity [2010], 5) | |
| A reaction: I have a repugnance to any sort of semantics that involves the objects themselves, even when dealing with proper names. If I talk of 'Napoleon', no small Frenchman is to be found anywhere in my sentences. |
| 14619 | The Quinean doubt: are semantics and facts separate, and do analytic sentences have no factual part? [Fine,K] |
| Full Idea: The source of the Quinean scepticism about analytic and synthetic is, first, scepticism over whether we can factor truth into a semantic and a factual component, and (second) if we can, is the factual component ever null? | |
| From: Kit Fine (Semantic Necessity [2010], 1) | |
| A reaction: You certainly can't grasp 'bachelors are unmarried men' if you haven't grasped the full Woosterian truth about men and marriage. But I could interdefine four meaningless words, so that you could employ them in analytic sentences. |