35 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] |
| 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] |
| 19400 | Possibles demand existence, so as many of them as possible must actually exist [Leibniz] |
| 19401 | God's sufficient reason for choosing reality is in the fitness or perfection of possibilities [Leibniz] |
| 5791 | Reduction is either by elimination, or by explanation [Searle] |
| 5799 | Eliminative reduction needs a gap between appearance and reality, as in sunsets [Searle] |
| 5790 | A property is 'emergent' if it is caused by elements of a system, when the elements lack the property [Searle] |
| 19402 | The actual universe is the richest composite of what is possible [Leibniz] |
| 5792 | Explanation of how we unify our mental stimuli into a single experience is the 'binding problem' [Searle] |
| 5786 | A system is either conscious or it isn't, though the intensity varies a lot [Searle] |
| 5794 | Consciousness has a first-person ontology, which only exists from a subjective viewpoint [Searle] |
| 5795 | There isn't one consciousness (information-processing) which can be investigated, and another (phenomenal) which can't [Searle] |
| 5788 | The use of 'qualia' seems to imply that consciousness and qualia are separate [Searle] |
| 5789 | I now think syntax is not in the physics, but in the eye of the beholder [Searle] |
| 5798 | Consciousness has a first-person ontology, so it cannot be reduced without omitting something [Searle] |
| 5787 | There is non-event causation between mind and brain, as between a table and its solidity [Searle] |
| 5797 | The pattern of molecules in the sea is much more complex than the complexity of brain neurons [Searle] |
| 5796 | If tree rings contain information about age, then age contains information about rings [Searle] |