43 ideas
| 20981 | What justifies reliance on reason? Is it just a tool? Why is it better than blind belief? [Sen] |
| 20982 | In politics and ethics, scrutiny from different perspectives is essential for objectivity [Sen] |
| 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] |
| 20990 | Rationality is conformity to reasons that can be sustained even after scrutiny [Sen] |
| 17722 | The concept 'red' is tied to what actually individuates red things [Peacocke] |
| 21005 | A human right is not plausible if public scrutiny might reject it [Sen] |
| 20983 | The original position insures that the agreements reached are fair [Sen] |
| 20987 | The veil of ignorance encourages neutral interests, but not a wider view of values [Sen] |
| 20984 | A social contract limits the pursuit of justice to members of a single society [Sen] |
| 20986 | A person's voice may count because of their interests, or because of their good sense [Sen] |
| 21001 | Famines tend to be caused by authoritarian rule [Sen] |
| 21002 | Effective democracy needs tolerant values [Sen] |
| 20999 | Democracy as 'government by discussion' now has wide support [Sen] |
| 20979 | Democracy needs more than some institutions; diverse sections of the people must be heard [Sen] |
| 20993 | Eradicating smallpox does not impoverish nature [Sen] |
| 20995 | Capabilities are part of freedom, involving real opportunities [Sen] |
| 20998 | Freedom can involve capabilities, independence and non-interference [Sen] |
| 20997 | The need for equality among people arises from impartiality and objectivity [Sen] |
| 20996 | All modern theories of justice demand equality of something [Sen] |
| 20988 | Freedom from torture or terrorist attacks is independent of citizenship [Sen] |
| 20980 | You don't need a complete theory of justice to see that slavery is wrong [Sen] |
| 20978 | Practical justice concerns not only ideals, but ways to achieve them [Sen] |
| 20985 | Our institutions should promote justice, rather than embodying it [Sen] |
| 20994 | We must focus on removing manifest injustice, not just try to design a perfect society [Sen] |
| 21000 | If justice needs public reasoning, which needs democracy, then justice and democracy are linked [Sen] |