76 ideas
| 9955 | Contextual definitions replace a complete sentence containing the expression [George/Velleman] |
| 10031 | Impredicative definitions quantify over the thing being defined [George/Velleman] |
| 3593 | The only way to specify the corresponding fact is asserting the sentence [Williams,M] |
| 3585 | Coherence needs positive links, not just absence of conflict [Williams,M] |
| 3584 | Justification needs coherence, while truth might be ideal coherence [Williams,M] |
| 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 |
| 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] |
| 3599 | Deduction shows entailments, not what to believe [Williams,M] |
| 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] |
| 12887 | A whole must have one characteristic, an internal relation, and a structure [Rescher/Oppenheim] |
| 3591 | We could never pin down how many beliefs we have [Williams,M] |
| 3582 | Propositions make error possible, so basic experiential knowledge is impossible [Williams,M] |
| 3592 | Phenomenalism is a form of idealism [Williams,M] |
| 3579 | Sense data avoid the danger of misrepresenting the world [Williams,M] |
| 3581 | Sense data can't give us knowledge if they are non-propositional [Williams,M] |
| 3564 | Is it people who are justified, or propositions? [Williams,M] |
| 8851 | Coherentists say that regress problems are assuming 'linear' justification [Williams,M] |
| 3595 | What works always takes precedence over theories [Williams,M] |
| 8849 | Traditional foundationalism is radically internalist [Williams,M] |
| 3580 | Experience must be meaningful to act as foundations [Williams,M] |
| 8853 | Basic judgements are immune from error because they have no content [Williams,M] |
| 3578 | Are empirical foundations judgements or experiences? [Williams,M] |
| 8855 | Sensory experience may be fixed, but it can still be misdescribed [Williams,M] |
| 3576 | Foundationalists are torn between adequacy and security [Williams,M] |
| 3577 | Strong justification eliminates error, but also reduces our true beliefs [Williams,M] |
| 3589 | Why should diverse parts of our knowledge be connected? [Williams,M] |
| 3590 | Coherence theory must give a foundational status to coherence itself [Williams,M] |
| 3571 | Externalism does not require knowing that you know [Williams,M] |
| 3574 | Externalism ignores the social aspect of knowledge [Williams,M] |
| 3569 | In the causal theory of knowledge the facts must cause the belief [Williams,M] |
| 3567 | How could there be causal relations to mathematical facts? [Williams,M] |
| 3586 | Only a belief can justify a belief [Williams,M] |
| 3573 | Externalist reliability refers to a range of conventional conditions [Williams,M] |
| 3565 | Sometimes I ought to distrust sources which are actually reliable [Williams,M] |
| 3566 | We control our beliefs by virtue of how we enquire [Williams,M] |
| 8852 | In the context of scepticism, externalism does not seem to be an option [Williams,M] |
| 3594 | Scepticism just reveals our limited ability to explain things [Williams,M] |
| 3575 | Scepticism can involve discrepancy, relativity, infinity, assumption and circularity [Williams,M] |
| 3587 | Seeing electrons in a cloud chamber requires theory [Williams,M] |
| 10110 | Corresponding to every concept there is a class (some of them sets) [George/Velleman] |
| 3588 | Foundationalists base meaning in words, coherentists base it in sentences [Williams,M] |