31 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] |
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] |
4020 | The modern self has disengaged reason, self-exploration, and personal commitment [Taylor,C] |
4002 | My aim is to map the connections between our sense of self and our moral understanding [Taylor,C] |
4006 | I can only be aware of myself as a person who changes by means of my personal history [Taylor,C] |
4003 | Selfhood and moral values are inextricably intertwined [Taylor,C] |
5049 | Intelligent pleasure is the perception of beauty, order and perfection [Leibniz] |
4021 | Willingness to risk life was the constitutive quality of the man of honour [Taylor,C] |
4005 | To have respect for people, you must feel their claims, or their injustices, or hold them in awe [Taylor,C] |
4004 | Consistency presupposes intrinsic description [Taylor,C] |
4010 | In later utilitarianism the modern stress on freedom leads to the rejection of paternalism [Taylor,C] |
5048 | Perfection is simply quantity of reality [Leibniz] |
4009 | Nominalists defended the sovereignty of God against the idea of natural existing good and evil [Taylor,C] |
5050 | Evil serves a greater good, and pain is necessary for higher pleasure [Leibniz] |