66 ideas
9955 | Contextual definitions replace a complete sentence containing the expression [George/Velleman] |
10031 | Impredicative definitions quantify over the thing being defined [George/Velleman] |
10098 | The 'power set' of A is all the subsets of A [George/Velleman] |
10099 | The 'ordered pair' <a, b>, for two sets a and b, is the set {{a, b},{a}} [George/Velleman] |
10101 | Cartesian Product A x B: the set of all ordered pairs in which a∈A and b∈B [George/Velleman] |
10103 | Grouping by property is common in mathematics, usually using equivalence [George/Velleman] |
10104 | 'Equivalence' is a reflexive, symmetric and transitive relation; 'same first letter' partitions English words [George/Velleman] |
10096 | Even the elements of sets in ZFC are sets, resting on the pure empty set [George/Velleman] |
10097 | Axiom of Extensionality: for all sets x and y, if x and y have the same elements then x = y [George/Velleman] |
10100 | Axiom of Pairing: for all sets x and y, there is a set z containing just x and y [George/Velleman] |
17900 | The Axiom of Reducibility made impredicative definitions possible [George/Velleman] |
10109 | ZFC can prove that there is no set corresponding to the concept 'set' [George/Velleman] |
10108 | As a reduction of arithmetic, set theory is not fully general, and so not logical [George/Velleman] |
10111 | Asserting Excluded Middle is a hallmark of realism about the natural world [George/Velleman] |
10129 | A 'model' is a meaning-assignment which makes all the axioms true [George/Velleman] |
10105 | Differences between isomorphic structures seem unimportant [George/Velleman] |
10119 | Consistency is a purely syntactic property, unlike the semantic property of soundness [George/Velleman] |
10126 | A 'consistent' theory cannot contain both a sentence and its negation [George/Velleman] |
10120 | Soundness is a semantic property, unlike the purely syntactic property of consistency [George/Velleman] |
10127 | A 'complete' theory contains either any sentence or its negation [George/Velleman] |
10106 | Rational numbers give answers to division problems with integers [George/Velleman] |
10102 | The integers are answers to subtraction problems involving natural numbers [George/Velleman] |
10107 | Real numbers provide answers to square root problems [George/Velleman] |
9946 | Logicists say mathematics is applicable because it is totally general [George/Velleman] |
10125 | The classical mathematician believes the real numbers form an actual set [George/Velleman] |
17899 | Second-order induction is stronger as it covers all concepts, not just first-order definable ones [George/Velleman] |
10128 | The Incompleteness proofs use arithmetic to talk about formal arithmetic [George/Velleman] |
17902 | A successor is the union of a set with its singleton [George/Velleman] |
10133 | Frege's Theorem shows the Peano Postulates can be derived from Hume's Principle [George/Velleman] |
10130 | Set theory can prove the Peano Postulates [George/Velleman] |
10089 | Talk of 'abstract entities' is more a label for the problem than a solution to it [George/Velleman] |
10131 | If mathematics is not about particulars, observing particulars must be irrelevant [George/Velleman] |
10092 | In the unramified theory of types, the types are objects, then sets of objects, sets of sets etc. [George/Velleman] |
10094 | The theory of types seems to rule out harmless sets as well as paradoxical ones. [George/Velleman] |
10095 | Type theory has only finitely many items at each level, which is a problem for mathematics [George/Velleman] |
17901 | Type theory prohibits (oddly) a set containing an individual and a set of individuals [George/Velleman] |
10114 | Bounded quantification is originally finitary, as conjunctions and disjunctions [George/Velleman] |
10134 | Much infinite mathematics can still be justified finitely [George/Velleman] |
10123 | The intuitionists are the idealists of mathematics [George/Velleman] |
10124 | Gödel's First Theorem suggests there are truths which are independent of proof [George/Velleman] |
14308 | We can bring dispositions into existence, as in creating an identifier [Dennett, by Mumford] |
7384 | Words are fixed by being attached to similarity clusters, without mention of 'essences' [Dennett] |
7374 | Light wavelengths entering the eye are only indirectly related to object colours [Dennett] |
7369 | Brains are essentially anticipation machines [Dennett] |
7393 | We can't draw a clear line between conscious and unconscious [Dennett] |
7367 | Perhaps the brain doesn't 'fill in' gaps in consciousness if no one is looking. [Dennett] |
7394 | Conscious events can only be explained in terms of unconscious events [Dennett] |
7391 | We can know a lot of what it is like to be a bat, and nothing important is unknown [Dennett] |
7387 | "Qualia" can be replaced by complex dispositional brain states [Dennett] |
7376 | We can't assume that dispositions will remain normal when qualia have been inverted [Dennett] |
7372 | In peripheral vision we see objects without their details, so blindsight is not that special [Dennett] |
7373 | Blindsight subjects glean very paltry information [Dennett] |
7385 | People accept blurred boundaries in many things, but insist self is All or Nothing [Dennett] |
7383 | The psychological self is an abstraction, not a thing in the brain [Dennett] |
7386 | Selves are not soul-pearls, but artefacts of social processes [Dennett] |
7381 | We tell stories about ourselves, to protect, control and define who we are [Dennett] |
7382 | We spin narratives about ourselves, and the audience posits a centre of gravity for them [Dennett] |
7370 | The brain is controlled by shifting coalitions, guided by good purposeful habits [Dennett] |
7379 | If an epiphenomenon has no physical effects, it has to be undetectable [Dennett] |
7365 | Dualism wallows in mystery, and to accept it is to give up [Dennett] |
7371 | All functionalism is 'homuncular', of one grain size or another [Dennett] |
7380 | Visual experience is composed of neural activity, which we find pleasing [Dennett] |
7366 | It is arbitrary to say which moment of brain processing is conscious [Dennett] |
10110 | Corresponding to every concept there is a class (some of them sets) [George/Velleman] |
7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |
7368 | Originally there were no reasons, purposes or functions; since there were no interests, there were only causes [Dennett] |