29 ideas
18928 | If maximalism is necessary, then that nothing exists has a truthmaker, which it can't have [Cameron] |
18931 | Determinate truths don't need extra truthmakers, just truthmakers that are themselves determinate [Cameron] |
18932 | The facts about the existence of truthmakers can't have a further explanation [Cameron] |
18923 | The present property 'having been F' says nothing about a thing's intrinsic nature [Cameron] |
18926 | One temporal distibution property grounds our present and past truths [Cameron] |
18929 | We don't want present truthmakers for the past, if they are about to cease to exist! [Cameron] |
13520 | A 'tautology' must include connectives [Wolf,RS] |
13524 | Deduction Theorem: T∪{P}|-Q, then T|-(P→Q), which justifies Conditional Proof [Wolf,RS] |
13521 | Universal Specification: ∀xP(x) implies P(t). True for all? Then true for an instance [Wolf,RS] |
13522 | Universal Generalization: If we prove P(x) with no special assumptions, we can conclude ∀xP(x) [Wolf,RS] |
13523 | Existential Generalization (or 'proof by example'): if we can say P(t), then we can say something is P [Wolf,RS] |
13529 | Empty Set: ∃x∀y ¬(y∈x). The unique empty set exists [Wolf,RS] |
13526 | Comprehension Axiom: if a collection is clearly specified, it is a set [Wolf,RS] |
13534 | In first-order logic syntactic and semantic consequence (|- and |=) nicely coincide [Wolf,RS] |
13535 | First-order logic is weakly complete (valid sentences are provable); we can't prove every sentence or its negation [Wolf,RS] |
13519 | Model theory uses sets to show that mathematical deduction fits mathematical truth [Wolf,RS] |
13531 | Model theory reveals the structures of mathematics [Wolf,RS] |
13532 | Model theory 'structures' have a 'universe', some 'relations', some 'functions', and some 'constants' [Wolf,RS] |
13533 | First-order model theory rests on completeness, compactness, and the Löwenheim-Skolem-Tarski theorem [Wolf,RS] |
13537 | An 'isomorphism' is a bijection that preserves all structural components [Wolf,RS] |
13539 | The LST Theorem is a serious limitation of first-order logic [Wolf,RS] |
13538 | If a theory is complete, only a more powerful language can strengthen it [Wolf,RS] |
13525 | Most deductive logic (unlike ordinary reasoning) is 'monotonic' - we don't retract after new givens [Wolf,RS] |
13530 | An ordinal is an equivalence class of well-orderings, or a transitive set whose members are transitive [Wolf,RS] |
13518 | Modern mathematics has unified all of its objects within set theory [Wolf,RS] |
18924 | Being polka-dotted is a 'spatial distribution' property [Cameron] |
18930 | Change is instantiation of a non-uniform distributional property, like 'being red-then-orange' [Cameron] |
6171 | Beliefs are states of the head that explain behaviour, and also items with referential truth-conditions [McGinn] |
18927 | Surely if things extend over time, then time itself must be extended? [Cameron] |