50 ideas
15945 | Second-order set theory just adds a version of Replacement that quantifies over functions [Lavine] |
15914 | An 'upper bound' is the greatest member of a subset; there may be several of these, so there is a 'least' one [Lavine] |
15921 | Collections of things can't be too big, but collections by a rule seem unlimited in size [Lavine] |
15937 | Those who reject infinite collections also want to reject the Axiom of Choice [Lavine] |
15936 | The Power Set is just the collection of functions from one collection to another [Lavine] |
15899 | Replacement was immediately accepted, despite having very few implications [Lavine] |
15930 | Foundation says descending chains are of finite length, blocking circularity, or ungrounded sets [Lavine] |
15898 | The controversy was not about the Axiom of Choice, but about functions as arbitrary, or given by rules [Lavine] |
15920 | Pure collections of things obey Choice, but collections defined by a rule may not [Lavine] |
15919 | The 'logical' notion of class has some kind of definition or rule to characterise the class [Lavine] |
15900 | The iterative conception of set wasn't suggested until 1947 [Lavine] |
15931 | The iterative conception needs the Axiom of Infinity, to show how far we can iterate [Lavine] |
15932 | The iterative conception doesn't unify the axioms, and has had little impact on mathematical proofs [Lavine] |
15933 | Limitation of Size: if it's the same size as a set, it's a set; it uses Replacement [Lavine] |
15913 | A collection is 'well-ordered' if there is a least element, and all of its successors can be identified [Lavine] |
15926 | Second-order logic presupposes a set of relations already fixed by the first-order domain [Lavine] |
15934 | Mathematical proof by contradiction needs the law of excluded middle [Lavine] |
15907 | Mathematics is nowadays (thanks to set theory) regarded as the study of structure, not of quantity [Lavine] |
15942 | Every rational number, unlike every natural number, is divisible by some other number [Lavine] |
15922 | For the real numbers to form a set, we need the Continuum Hypothesis to be true [Lavine] |
18250 | Cauchy gave a necessary condition for the convergence of a sequence [Lavine] |
15904 | The two sides of the Cut are, roughly, the bounding commensurable ratios [Lavine] |
15912 | Counting results in well-ordering, and well-ordering makes counting possible [Lavine] |
15949 | The theory of infinity must rest on our inability to distinguish between very large sizes [Lavine] |
15947 | The infinite is extrapolation from the experience of indefinitely large size [Lavine] |
15940 | The intuitionist endorses only the potential infinite [Lavine] |
15909 | 'Aleph-0' is cardinality of the naturals, 'aleph-1' the next cardinal, 'aleph-ω' the ω-th cardinal [Lavine] |
15915 | Ordinals are basic to Cantor's transfinite, to count the sets [Lavine] |
15917 | Paradox: the class of all ordinals is well-ordered, so must have an ordinal as type - giving a bigger ordinal [Lavine] |
15918 | Paradox: there is no largest cardinal, but the class of everything seems to be the largest [Lavine] |
15929 | Set theory will found all of mathematics - except for the notion of proof [Lavine] |
15935 | Modern mathematics works up to isomorphism, and doesn't care what things 'really are' [Lavine] |
15928 | Intuitionism rejects set-theory to found mathematics [Lavine] |
20339 | Classes rarely share properties with their members - unlike universals and types [Wollheim] |
16463 | Adams says actual things have haecceities, but not things that only might exist [Adams,RM, by Stalnaker] |
20338 | We often treat a type as if it were a sort of token [Wollheim] |
20342 | Interpretation is performance for some arts, and critical for all arts [Wollheim] |
20343 | A love of nature must precede a love of art [Wollheim] |
20348 | A criterion of identity for works of art would be easier than a definition [Wollheim] |
20347 | If beauty needs organisation, then totally simple things can't be beautiful [Wollheim] |
20331 | It is claimed that the expressive properties of artworks are non-physical [Wollheim] |
20345 | Some say art must have verbalisable expression, and others say the opposite! [Wollheim] |
20337 | The traditional view is that knowledge of its genre to essential to appreciating literature [Wollheim] |
20336 | Style can't be seen directly within a work, but appreciation needs a grasp of style [Wollheim] |
20333 | If artworks are not physical objects, they are either ideal entities, or collections of phenomena [Wollheim] |
20334 | The ideal theory says art is an intuition, shaped by a particular process, and presented in public [Wollheim] |
20335 | The ideal theory of art neglects both the audience and the medium employed [Wollheim] |
20340 | A musical performance has virtually the same features as the piece of music [Wollheim] |
20341 | An interpretation adds further properties to the generic piece of music [Wollheim] |
20332 | A drawing only represents Napoleon if the artist intended it to [Wollheim] |