112 ideas
| 9408 | Science studies phenomena, but only metaphysics tells us what exists [Mumford] |
| 9429 | Many forms of reasoning, such as extrapolation and analogy, are useful but deductively invalid [Mumford] |
| 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] |
| 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] |
| 9427 | For Humeans the world is a world primarily of events [Mumford] |
| 14334 | Modest realism says there is a reality; the presumptuous view says we can accurately describe it [Mumford] |
| 14306 | Anti-realists deny truth-values to all statements, and say evidence and ontology are inseparable [Mumford] |
| 14333 | Dispositions and categorical properties are two modes of presentation of the same thing [Mumford] |
| 14336 | Categorical predicates are those unconnected to functions [Mumford] |
| 14315 | Categorical properties and dispositions appear to explain one another [Mumford] |
| 14332 | There are four reasons for seeing categorical properties as the most fundamental [Mumford] |
| 14302 | A lead molecule is not leaden, and macroscopic properties need not be microscopically present [Mumford] |
| 14294 | Dispositions are attacked as mere regularities of events, or place-holders for unknown properties [Mumford] |
| 9446 | Properties are just natural clusters of powers [Mumford] |
| 14316 | If dispositions have several categorical realisations, that makes the two separate [Mumford] |
| 14310 | Dispositions are classifications of properties by functional role [Mumford] |
| 14317 | I say the categorical base causes the disposition manifestation [Mumford] |
| 14313 | All properties must be causal powers (since they wouldn't exist otherwise) [Mumford] |
| 14318 | Intrinsic properties are just causal powers, and identifying a property as causal is then analytic [Mumford] |
| 14298 | Dispositions can be contrasted either with occurrences, or with categorical properties [Mumford] |
| 14293 | Dispositions are ascribed to at least objects, substances and persons [Mumford] |
| 14326 | Unlike categorical bases, dispositions necessarily occupy a particular causal role [Mumford] |
| 14314 | If dispositions are powers, background conditions makes it hard to say what they do [Mumford] |
| 14325 | Maybe dispositions can replace powers in metaphysics, as what induces property change [Mumford] |
| 14312 | Orthodoxy says dispositions entail conditionals (rather than being equivalent to them) [Mumford] |
| 14291 | Dispositions are not just possibilities - they are features of actual things [Mumford] |
| 14299 | There could be dispositions that are never manifested [Mumford] |
| 14323 | If every event has a cause, it is easy to invent a power to explain each case [Mumford] |
| 14328 | Traditional powers initiate change, but are mysterious between those changes [Mumford] |
| 14331 | Categorical eliminativists say there are no dispositions, just categorical states or mechanisms [Mumford] |
| 9435 | A 'porridge' nominalist thinks we just divide reality in any way that suits us [Mumford] |
| 9447 | If properties are clusters of powers, this can explain why properties resemble in degrees [Mumford] |
| 18617 | Substances, unlike aggregates, can survive a change of parts [Mumford] |
| 14295 | Many artefacts have dispositional essences, which make them what they are [Mumford] |
| 12248 | How can we show that a universally possessed property is an essential property? [Mumford] |
| 18618 | Maybe possibilities are recombinations of the existing elements of reality [Mumford] |
| 18619 | Combinatorial possibility has to allow all elements to be combinable, which seems unlikely [Mumford] |
| 18620 | Combinatorial possibility relies on what actually exists (even over time), but there could be more [Mumford] |
| 14309 | Truth-functional conditionals can't distinguish whether they are causal or accidental [Mumford] |
| 14311 | Dispositions are not equivalent to stronger-than-material conditionals [Mumford] |
| 14319 | Nomothetic explanations cite laws, and structural explanations cite mechanisms [Mumford] |
| 14342 | General laws depend upon the capacities of particulars, not the other way around [Mumford] |
| 14322 | If fragile just means 'breaks when dropped', it won't explain a breakage [Mumford] |
| 14337 | Maybe dispositions can replace the 'laws of nature' as the basis of explanation [Mumford] |
| 14343 | To avoid a regress in explanations, ungrounded dispositions will always have to be posited [Mumford] |
| 14320 | Subatomic particles may terminate explanation, if they lack structure [Mumford] |
| 14324 | Ontology is unrelated to explanation, which concerns modes of presentation and states of knowledge [Mumford] |
| 10110 | Corresponding to every concept there is a class (some of them sets) [George/Velleman] |
| 20930 | The existence of law is one thing, its merits and demerits another [Austin,J] |
| 14344 | Natural kinds, such as electrons, all behave the same way because we divide them by dispositions [Mumford] |
| 19068 | Causation interests us because we want to explain change [Mumford] |
| 9430 | Singular causes, and identities, might be necessary without falling under a law [Mumford] |
| 9445 | We can give up the counterfactual account if we take causal language at face value [Mumford] |
| 9443 | It is only properties which are the source of necessity in the world [Mumford] |
| 14338 | In the 'laws' view events are basic, and properties are categorical, only existing when manifested [Mumford] |
| 9444 | There are four candidates for the logical form of law statements [Mumford] |
| 14339 | Without laws, how can a dispositionalist explain general behaviour within kinds? [Mumford] |
| 14341 | Dretske and Armstrong base laws on regularities between individual properties, not between events [Mumford] |
| 9441 | Regularity laws don't explain, because they have no governing role [Mumford] |
| 14340 | It is a regularity that whenever a person sneezes, someone (somewhere) promptly coughs [Mumford] |
| 9431 | Pure regularities are rare, usually only found in idealized conditions [Mumford] |
| 9416 | Regularities are more likely with few instances, and guaranteed with no instances! [Mumford] |
| 9415 | Would it count as a regularity if the only five As were also B? [Mumford] |
| 9422 | If the best system describes a nomological system, the laws are in nature, not in the description [Mumford] |
| 9421 | The best systems theory says regularities derive from laws, rather than constituting them [Mumford] |
| 9432 | Laws of nature are necessary relations between universal properties, rather than about particulars [Mumford] |
| 9433 | If laws can be uninstantiated, this favours the view of them as connecting universals [Mumford] |
| 14345 | The necessity of an electron being an electron is conceptual, and won't ground necessary laws [Mumford] |
| 9434 | Laws of nature are just the possession of essential properties by natural kinds [Mumford] |
| 14307 | Some dispositions are so far unknown, until we learn how to manifest them [Mumford] |
| 9437 | To distinguish accidental from essential properties, we must include possible members of kinds [Mumford] |
| 9439 | The Central Dilemma is how to explain an internal or external view of laws which govern [Mumford] |
| 9412 | You only need laws if you (erroneously) think the world is otherwise inert [Mumford] |
| 9411 | There are no laws of nature in Aristotle; they became standard with Descartes and Newton [Mumford] |