27 ideas
2676 | Didactic argument starts from the principles of the subject, not from the opinions of the learner [Aristotle] |
2675 | Reasoning is a way of making statements which makes them lead on to other statements [Aristotle] |
2677 | Dialectic aims to start from generally accepted opinions, and lead to a contradiction [Aristotle] |
2674 | Competitive argument aims at refutation, fallacy, paradox, solecism or repetition [Aristotle] |
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] |
16967 | 'Are Coriscus and Callias at home?' sounds like a single question, but it isn't [Aristotle] |
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] |
17757 | Members of ordinals are ordinals, and also subsets of ordinals [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] |
17758 | Ordinals are transitive sets of transitive sets; or transitive sets totally ordered by inclusion [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] |
16149 | Generic terms like 'man' are not substances, but qualities, relations, modes or some such thing [Aristotle] |
11840 | Only if two things are identical do they have the same attributes [Aristotle] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
19216 | Propositions (such as 'that dog is barking') only exist if their items exist [Williamson] |