51 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] |
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] |
4568 | If 'Queen of England' does not refer if there is no queen, its meaning can't refer if there is one [Cooper,DE] |
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] |
4574 | If some peoples do not have categories like time or cause, they can't be essential features of rationality [Cooper,DE] |
4573 | If it is claimed that language correlates with culture, we must be able to identify the two independently [Cooper,DE] |
4575 | A person's language doesn't prove their concepts, but how are concepts deduced apart from language? [Cooper,DE] |
2170 | Homer does not distinguish between soul and body [Homer, by Williams,B] |
4561 | Many sentences set up dispositions which are irrelevant to the meanings of the sentences [Cooper,DE] |
4564 | I can meaningfully speculate that humans may have experiences currently impossible for us [Cooper,DE] |
4565 | The verification principle itself seems neither analytic nor verifiable [Cooper,DE] |
4563 | 'How now brown cow?' is used for elocution, but this says nothing about its meaning [Cooper,DE] |
4562 | Most people know how to use the word "Amen", but they do not know what it means [Cooper,DE] |
4571 | Reference need not be a hit-or-miss affair [Cooper,DE] |
4566 | Any thesis about reference is also a thesis about what exists to be referred to [Cooper,DE] |
4572 | If predicates name things, that reduces every sentence to a mere list of names [Cooper,DE] |
4576 | An analytic truth is one which becomes a logical truth when some synonyms have been replaced [Cooper,DE] |
2171 | The 'will' doesn't exist; there is just conclusion, then action [Homer, by Williams,B] |
21819 | Plato says the Good produces the Intellectual-Principle, which in turn produces the Soul [Homer, by Plotinus] |
11388 | Let there be one ruler [Homer] |
14829 | Homer so enjoys the company of the gods that he must have been deeply irreligious [Homer, by Nietzsche] |