29 ideas
19259 | If 2-D conceivability can a priori show possibilities, this is a defence of conceptual analysis [Vaidya] |
17749 | Post proved the consistency of propositional logic in 1921 [Walicki] |
17765 | Propositional language can only relate statements as the same or as different [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] |
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] |
17763 | Axiomatic systems are purely syntactic, and do not presuppose any interpretation [Walicki] |
17761 | A compact axiomatisation makes it possible to understand a field as a whole [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] |
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] |
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] |
19262 | Essential properties are necessary, but necessary properties may not be essential [Vaidya] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
19267 | Define conceivable; how reliable is it; does inconceivability help; and what type of possibility results? [Vaidya] |
19440 | How do you know you have conceived a thing deeply enough to assess its possibility? [Vaidya] |
19268 | Inconceivability (implying impossibility) may be failure to conceive, or incoherence [Vaidya] |
19265 | Can you possess objective understanding without realising it? [Vaidya] |
19260 | Gettier deductive justifications split the justification from the truthmaker [Vaidya] |
19266 | In a disjunctive case, the justification comes from one side, and the truth from the other [Vaidya] |
3061 | Anaxarchus said that he was not even sure that he knew nothing [Anaxarchus, by Diog. Laertius] |
19264 | Aboutness is always intended, and cannot be accidental [Vaidya] |