54 ideas
23728 | Analysis aims to express the full set of platitudes surrounding a given concept [Smith,M] |
23744 | Defining a set of things by paradigms doesn't pin them down enough [Smith,M] |
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] |
3643 | The concept of mind excludes body, and vice versa [Descartes] |
23743 | Capturing all the common sense facts about rationality is almost impossible [Smith,M] |
23736 | A person can have a desire without feeling it [Smith,M] |
23735 | Subjects may be fallible about the desires which explain their actions [Smith,M] |
23738 | Humeans (unlike their opponents) say that desires and judgements can separate [Smith,M] |
23723 | In the Humean account, desires are not true/false, or subject to any rational criticism [Smith,M] |
23724 | A pure desire could be criticised if it were based on a false belief [Smith,M] |
23739 | Goals need desires, and so only desires can motivate us [Smith,M] |
23742 | If first- and second-order desires conflict, harmony does not require the second-order to win [Smith,M] |
23746 | Objective reasons to act might be the systematic desires of a fully rational person [Smith,M] |
23733 | Motivating reasons are psychological, while normative reasons are external [Smith,M] |
23740 | Humeans take maximising desire satisfaction as the normative reasons for actions [Smith,M] |
23745 | We cannot expect even fully rational people to converge on having the same desires for action [Smith,M] |
23731 | 'Externalists' say moral judgements are not reasons, and maybe not even motives [Smith,M] |
23732 | A person could make a moral judgement without being in any way motivated by it [Smith,M] |
23729 | Moral internalism says a judgement of rightness is thereby motivating [Smith,M] |
23730 | 'Rationalism' says the rightness of an action is a reason to perform it [Smith,M] |
23727 | Expressivists count attitudes as 'moral' if they concern features of things, rather than their mere existence [Smith,M] |
23741 | Is valuing something a matter of believing or a matter of desiring? [Smith,M] |