53 ideas
| 14179 | The finest branch of wisdom is justice and moderation in ordering states and families [Plato] |
| 3695 | Philosophy is a priori if it is anything [Bonjour] |
| 3651 | Perceiving necessary connections is the essence of reasoning [Bonjour] |
| 3700 | Coherence can't be validated by appeal to coherence [Bonjour] |
| 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] |
| 1607 | Diotima said the Forms are the objects of desire in philosophical discourse [Plato, by Roochnik] |
| 3697 | The concept of possibility is prior to that of necessity [Bonjour] |
| 3704 | Moderate rationalists believe in fallible a priori justification [Bonjour] |
| 3707 | Our rules of thought can only be judged by pure rational insight [Bonjour] |
| 174 | True opinion without reason is midway between wisdom and ignorance [Plato] |
| 3706 | A priori justification can vary in degree [Bonjour] |
| 3696 | A priori justification requires understanding but no experience [Bonjour] |
| 3703 | You can't explain away a priori justification as analyticity, and you can't totally give it up [Bonjour] |
| 3699 | The induction problem blocks any attempted proof of physical statements [Bonjour] |
| 3701 | Externalist theories of justification don't require believers to have reasons for their beliefs [Bonjour] |
| 3702 | Externalism means we have no reason to believe, which is strong scepticism [Bonjour] |
| 3709 | Induction must go beyond the evidence, in order to explain why the evidence occurred [Bonjour] |
| 180 | We call a person the same throughout life, but all their attributes change [Plato] |
| 181 | Only the gods stay unchanged; we replace our losses with similar acquisitions [Plato] |
| 3708 | All thought represents either properties or indexicals [Bonjour] |
| 3698 | Indeterminacy of translation is actually indeterminacy of meaning and belief [Bonjour] |
| 4026 | Beauty is harmony with what is divine, and ugliness is lack of such harmony [Plato] |
| 172 | Love of ugliness is impossible [Plato] |
| 173 | Beauty and goodness are the same [Plato] |
| 183 | Stage two is the realisation that beauty of soul is of more value than beauty of body [Plato] |
| 184 | Progress goes from physical beauty, to moral beauty, to the beauty of knowledge, and reaches absolute beauty [Plato] |
| 171 | Music is a knowledge of love in the realm of harmony and rhythm [Plato] |
| 176 | Love follows beauty, wisdom is exceptionally beautiful, so love follows wisdom [Plato] |
| 14177 | Love assists men in achieving merit and happiness [Plato] |
| 179 | Love is desire for perpetual possession of the good [Plato] |
| 177 | If a person is good they will automatically become happy [Plato] |
| 14178 | Happiness is secure enjoyment of what is good and beautiful [Plato] |
| 170 | The only slavery which is not dishonourable is slavery to excellence [Plato] |
| 182 | The first step on the right path is the contemplation of physical beauty when young [Plato] |
| 175 | Gods are not lovers of wisdom, because they are already wise [Plato] |