41 ideas
13520 | A 'tautology' must include connectives [Wolf,RS] |
13524 | Deduction Theorem: T∪{P}|-Q, then T|-(P→Q), which justifies Conditional Proof [Wolf,RS] |
13522 | Universal Generalization: If we prove P(x) with no special assumptions, we can conclude ∀xP(x) [Wolf,RS] |
13521 | Universal Specification: ∀xP(x) implies P(t). True for all? Then true for an instance [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] |
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] |
13519 | Model theory uses sets to show that mathematical deduction fits mathematical truth [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] |
16062 | A necessary relation between fact-levels seems to be a further irreducible fact [Lynch/Glasgow] |
16061 | If some facts 'logically supervene' on some others, they just redescribe them, adding nothing [Lynch/Glasgow] |
16060 | Nonreductive materialism says upper 'levels' depend on lower, but don't 'reduce' [Lynch/Glasgow] |
16064 | The hallmark of physicalism is that each causal power has a base causal power under it [Lynch/Glasgow] |
5806 | Belief is the power of metarepresentation [Dretske] |
5801 | A mouse hearing a piano played does not believe it, because it lacks concepts and understanding [Dretske] |
6445 | You have knowledge if you can rule out all the relevant alternatives to what you believe [Dretske, by DeRose] |
19544 | Closure says if you know P, and also know P implies Q, then you must know Q [Dretske] |
19545 | We needn't regret the implications of our regrets; regretting drinking too much implies the past is real [Dretske] |
19547 | Reasons for believing P may not transmit to its implication, Q [Dretske] |
19546 | Knowing by visual perception is not the same as knowing by implication [Dretske] |
19548 | The only way to preserve our homely truths is to abandon closure [Dretske] |
19549 | P may imply Q, but evidence for P doesn't imply evidence for Q, so closure fails [Dretske] |
19550 | We know past events by memory, but we don't know the past is real (an implication) by memory [Dretske] |
5802 | Representations are in the head, but their content is not, as stories don't exist in their books [Dretske] |
5809 | Some activities are performed better without consciousness of them [Dretske] |
5808 | Qualia are just the properties objects are represented as having [Dretske] |
5803 | In a representational theory of mind, introspection is displaced perception [Dretske] |
5807 | Introspection is the same as the experience one is introspecting [Dretske] |
5805 | Introspection does not involve looking inwards [Dretske] |
5804 | A representational theory of the mind is an externalist theory of the mind [Dretske] |
5800 | All mental facts are representation, which consists of informational functions [Dretske] |