58 ideas
12249 | 'Animal' is a genus and 'rational' is a specific difference [Oderberg] |
12242 | Definition distinguishes one kind from another, and individuation picks out members of the kind [Oderberg] |
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] |
15920 | Pure collections of things obey Choice, but collections defined by a rule may not [Lavine] |
15898 | The controversy was not about the Axiom of Choice, but about functions as arbitrary, or given by rules [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] |
6007 | If you know your father, but don't recognise your father veiled, you know and don't know the same person [Eubulides, by Dancy,R] |
6006 | If you say truly that you are lying, you are lying [Eubulides, by Dancy,R] |
6008 | Removing one grain doesn't destroy a heap, so a heap can't be destroyed [Eubulides, by Dancy,R] |
15907 | Mathematics is nowadays (thanks to set theory) regarded as the study of structure, not of quantity [Lavine] |
12238 | The Aristotelian view is that numbers depend on (and are abstracted from) other things [Oderberg] |
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] |
12254 | Being is substantial/accidental, complete/incomplete, necessary/contingent, possible, relative, intrinsic.. [Oderberg] |
12253 | If tropes are in space and time, in what sense are they abstract? [Oderberg] |
12256 | We need to distinguish the essential from the non-essential powers [Oderberg] |
12252 | Empiricists gave up 'substance', as unknowable substratum, or reducible to a bundle [Oderberg] |
12241 | Essences are real, about being, knowable, definable and classifiable [Oderberg, by PG] |
12244 | Nominalism is consistent with individual but not with universal essences [Oderberg] |
12240 | Essentialism is the main account of the unity of objects [Oderberg] |
12247 | Essence is not explanatory but constitutive [Oderberg] |
12258 | Properties are not part of an essence, but they flow from it [Oderberg] |
12257 | Could we replace essence with collections of powers? [Oderberg] |
12236 | Leibniz's Law is an essentialist truth [Oderberg] |
12250 | Bodies have act and potency, the latter explaining new kinds of existence [Oderberg] |
12234 | Realism about possible worlds is circular, since it needs a criterion of 'possible' [Oderberg] |
12235 | Necessity of identity seems trivial, because it leaves out the real essence [Oderberg] |
12237 | Rigid designation has at least three essentialist presuppositions [Oderberg] |
12245 | Essence is the source of a thing's characteristic behaviour [Oderberg] |
12246 | What makes Parmenidean reality a One rather than a Many? [Oderberg] |
12239 | The real essentialist is not merely a scientist [Oderberg] |
12243 | The reductionism found in scientific essentialism is mistaken [Oderberg] |