15 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) |
| 10397 | Abelard's mereology involves privileged and natural divisions, and principal parts [Abelard, by King,P] |
| Full Idea: Abelard's theory of substantial integral wholes is not a pure mereology in the modern sense, since he holds that there are privileged divisions; ..the division of a whole must be into its principal parts. Some wholes have a natural division. | |
| From: report of Peter Abelard (works [1135]) by Peter King - Peter Abelard 2 | |
| A reaction: This is a mereology that cuts nature at the joints, rather than Lewis's 'unrestricted composition', so I find Abelard rather appealing. |
| 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) |
| 10396 | If 'animal' is wholly present in Socrates and an ass, then 'animal' is rational and irrational [Abelard, by King,P] |
| Full Idea: Abelard argued that if the universal 'animal' were completely present in both Socrates and an ass, making each wholly an animal, then the same thing, animal, will be simultaneously rational and irrational, with contraries present in the whole thing. | |
| From: report of Peter Abelard (works [1135]) by Peter King - Peter Abelard 2 | |
| A reaction: If we have universals for rationality and irrationality, they can distinguish the two. But we must also say that rationality is not an aspect of animal, which seems to mean that mind isn't either. What is the essence of an animal? Not reason? |
| 10395 | Abelard was an irrealist about virtually everything apart from concrete individuals [Abelard, by King,P] |
| Full Idea: Abelard was an irrealist about universals, but also about propositions, events, times other than the present, natural kinds, relations, wholes, absolute space, hylomorphic composites, and the like. The concrete individual is enough to populate the world. | |
| From: report of Peter Abelard (works [1135]) by Peter King - Peter Abelard 2 | |
| A reaction: If a Nominalist claims that 'only particulars exist', this makes him an extreme nominalist, and remarkably materialistic for his time (though he accepted the soul, as well as God). |
| 15384 | Only words can be 'predicated of many'; the universality is just in its mode of signifying [Abelard, by Panaccio] |
| Full Idea: Abelard concluded that only words can be 'predicated of many'. A universal is nothing but a general linguistic predicate, and its universality depends not on its mode of being, but on its mode of signifying. | |
| From: report of Peter Abelard (works [1135]) by Claude Panaccio - Medieval Problem of Universals 'Peter' | |
| A reaction: Abelard seems to be the originator of what is now called Predicate Nominalism, with Nelson Goodman as his modern representative. If it is just words, is there no fact of two things having the 'same' property? |
| 16640 | Form is the principle that connects a thing's constitution (rather than being operative) [Hill,N] |
| Full Idea: Form is the state and condition of a thing, a result of the connection among its material principles; it is a constituting principle, not an operative one. | |
| From: Nicholas Hill (Philosophia Epicurea [1610], n 35) | |
| A reaction: Pasnau presents this as a denial of form, but it looks to me like someone fishing for what form could be in a more scientific context. Aristotle would have approved of 'principles'. Hill seems to defend the categorical against the dispositional. |
| 8481 | The de dicto-de re modality distinction dates back to Abelard [Abelard, by Orenstein] |
| Full Idea: The de dicto-de re modality distinction dates back to Abelard. | |
| From: report of Peter Abelard (works [1135]) by Alex Orenstein - W.V. Quine Ch.7 | |
| A reaction: Most modern philosophers couldn't (apparently) care less where a concept originated, but one of the principles of this database is that such things do matter. I'm not sure why, but if we want the whole picture, we need the historical picture. |
| 15385 | Abelard's problem is the purely singular aspects of things won't account for abstraction [Panaccio on Abelard] |
| Full Idea: Abelard's problem is that it is not clear how singular forms could do the job they are supposed to do - to account for abstraction, namely - if they were purely singular aspects. | |
| From: comment on Peter Abelard (works [1135]) by Claude Panaccio - Medieval Problem of Universals 'Peter' | |
| A reaction: A very nice question! If we say that abstracta are just acquired by ignoring all but that feature in some objects, how do we identify 'that' feature in order to select it? The instances must share something in common to be abstracted. |
| 15383 | Nothing external can truly be predicated of an object [Abelard, by Panaccio] |
| Full Idea: Abelard argued from the commonly accepted definition of a universal as 'what can be predicated of man', that no external thing can ever be predicated of anything. | |
| From: report of Peter Abelard (works [1135]) by Claude Panaccio - Medieval Problem of Universals 'Peter' | |
| A reaction: It sounds to me as if Abelard is confusing predicates with properties! Maybe no external can be a property of anything, but I take predicates to just be part of what you can say about anything, and that had better included external facts. |
| 10398 | Natural kinds are not special; they are just well-defined resemblance collections [Abelard, by King,P] |
| Full Idea: In Abelard's view a natural kind is a well-defined collection of things that have the same features, so that natural kinds have no special status, being no more than discrete integral wholes whose principle of membership is similarity. | |
| From: report of Peter Abelard (works [1135]) by Peter King - Peter Abelard 2 | |
| A reaction: I take a natural kind to be a completely stable and invariant class of things. Presumably this invariance has an underlying explanation, but Abelard seems to take the Humean line that we cannot penetrate beyond the experienced surface. |