73 ideas
| 16241 | The metaphysics of nature should focus on physics [Maudlin] |
| 16257 | Kant survives in seeing metaphysics as analysing our conceptual system, which is a priori [Maudlin] |
| 16276 | Wide metaphysical possibility may reduce metaphysics to analysis of fantasies [Maudlin] |
| 16244 | If the universe is profligate, the Razor leads us astray [Maudlin] |
| 16255 | The Razor rightly prefers one cause of multiple events to coincidences of causes [Maudlin] |
| 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 |
| 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] |
| 17901 | Type theory prohibits (oddly) a set containing an individual and a set of individuals [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] |
| 10134 | Much infinite mathematics can still be justified finitely [George/Velleman] |
| 10114 | Bounded quantification is originally finitary, as conjunctions and disjunctions [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] |
| 16243 | The Humean view is wrong; laws and direction of time are primitive, and atoms are decided by physics [Maudlin] |
| 16271 | Lewis says it supervenes on the Mosaic, but actually thinks the Mosaic is all there is [Maudlin] |
| 16273 | If the Humean Mosaic is ontological bedrock, there can be no explanation of its structure [Maudlin] |
| 16275 | The 'spinning disc' is just impossible, because there cannot be 'homogeneous matter' [Maudlin] |
| 16258 | To get an ontology from ontological commitment, just add that some theory is actually true [Maudlin] |
| 16259 | Naďve translation from natural to formal language can hide or multiply the ontology [Maudlin] |
| 16253 | A property is fundamental if two objects can differ in only that respect [Maudlin] |
| 16263 | Fundamental physics seems to suggest there are no such things as properties [Maudlin] |
| 16260 | Existence of universals may just be decided by acceptance, or not, of second-order logic [Maudlin] |
| 16277 | Logically impossible is metaphysically impossible, but logically possible is not metaphysically possible [Maudlin] |
| 16249 | A counterfactual antecedent commands the redescription of a selected moment [Maudlin] |
| 16254 | Induction leaps into the unknown, but usually lands safely [Maudlin] |
| 16245 | Laws should help explain the things they govern, or that manifest them [Maudlin] |
| 10110 | Corresponding to every concept there is a class (some of them sets) [George/Velleman] |
| 19399 | Prime matter is nothing when it is at rest [Leibniz] |
| 16248 | Evaluating counterfactuals involves context and interests [Maudlin] |
| 16250 | We don't pick a similar world from many - we construct one possibility from the description [Maudlin] |
| 16268 | The counterfactual is ruined if some other cause steps in when the antecedent fails [Maudlin] |
| 16267 | If we know the cause of an event, we seem to assent to the counterfactual [Maudlin] |
| 16269 | If the effect hadn't occurred the cause wouldn't have happened, so counterfactuals are two-way [Maudlin] |
| 16242 | Laws of nature are ontological bedrock, and beyond analysis [Maudlin] |
| 16247 | Laws are primitive, so two indiscernible worlds could have the same laws [Maudlin] |
| 16272 | Fundamental laws say how nature will, or might, evolve from some initial state [Maudlin] |
| 16251 | 'Humans with prime house numbers are mortal' is not a law, because not a natural kind [Maudlin] |
| 16270 | If laws are just regularities, then there have to be laws [Maudlin] |
| 16264 | I believe the passing of time is a fundamental fact about the world [Maudlin] |
| 16265 | If time passes, presumably it passes at one second per second [Maudlin] |
| 16266 | There is one ordered B series, but an infinitude of A series, depending on when the present is [Maudlin] |