39 ideas
11223 | Definitions usually have a term, a 'definiendum' containing the term, and a defining 'definiens' [Gupta] |
11215 | Notable definitions have been of piety (Plato), God (Anselm), number (Frege), and truth (Tarski) [Gupta] |
11225 | A definition needs to apply to the same object across possible worlds [Gupta] |
11227 | The 'revision theory' says that definitions are rules for improving output [Gupta] |
11226 | Traditional definitions need: same category, mention of the term, and conservativeness and eliminability [Gupta] |
11221 | A definition can be 'extensionally', 'intensionally' or 'sense' adequate [Gupta] |
11224 | Traditional definitions are general identities, which are sentential and reductive [Gupta] |
11217 | Chemists aim at real definition of things; lexicographers aim at nominal definition of usage [Gupta] |
11216 | If definitions aim at different ideals, then defining essence is not a unitary activity [Gupta] |
11218 | Stipulative definition assigns meaning to a term, ignoring prior meanings [Gupta] |
11220 | Ostensive definitions look simple, but are complex and barely explicable [Gupta] |
14965 | Truth rests on Elimination ('A' is true → A) and Introduction (A → 'A' is true) [Gupta] |
14968 | A weakened classical language can contain its own truth predicate [Gupta] |
17765 | Propositional language can only relate statements as the same or as different [Walicki] |
17749 | Post proved the consistency of propositional logic in 1921 [Walicki] |
17764 | Boolean connectives are interpreted as functions on the set {1,0} [Walicki] |
17752 | The empty set is useful for defining sets by properties, when the members are not yet known [Walicki] |
17753 | The empty set avoids having to take special precautions in case members vanish [Walicki] |
11222 | The ordered pair <x,y> is defined as the set {{x},{x,y}}, capturing function, not meaning [Gupta] |
17759 | Ordinals play the central role in set theory, providing the model of well-ordering [Walicki] |
17741 | To determine the patterns in logic, one must identify its 'building blocks' [Walicki] |
17747 | A 'model' of a theory specifies interpreting a language in a domain to make all theorems true [Walicki] |
17748 | The L-S Theorem says no theory (even of reals) says more than a natural number theory [Walicki] |
17761 | A compact axiomatisation makes it possible to understand a field as a whole [Walicki] |
17763 | Axiomatic systems are purely syntactic, and do not presuppose any interpretation [Walicki] |
14964 | The Liar reappears, even if one insists on propositions instead of sentences [Gupta] |
14969 | Strengthened Liar: either this sentence is neither-true-nor-false, or it is not true [Gupta] |
17755 | Ordinals are the empty set, union with the singleton, and any arbitrary union of ordinals [Walicki] |
17756 | The union of finite ordinals is the first 'limit ordinal'; 2ω is the second... [Walicki] |
17757 | Members of ordinals are ordinals, and also subsets of ordinals [Walicki] |
17758 | Ordinals are transitive sets of transitive sets; or transitive sets totally ordered by inclusion [Walicki] |
17760 | Two infinite ordinals can represent a single infinite cardinal [Walicki] |
17762 | In non-Euclidean geometry, all Euclidean theorems are valid that avoid the fifth postulate [Walicki] |
17754 | Inductive proof depends on the choice of the ordering [Walicki] |
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] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |