28 ideas
20744 | Phenomenologists say all experience is about something and is directed [Aho] |
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] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
20736 | Science has to abstract out the subjective attributes of things, focusing on what is objective [Aho] |
20734 | Anxiety, nausea, guilt and absurdity shake us up, revealing our freedom and limits [Aho] |
20733 | Our 'existence' is how we create ourselves, unconstrained by any prior 'essence' [Aho] |
20753 | The self is constituted by its choices made within a social context [Aho] |
20738 | Social contracts and markets have made society seem disconnected and artificial [Aho] |
20737 | Protestantism brought the modern emphasis on inner states of the soul [Aho] |
16689 | The schools said spirits lack extension, and wonder how many could dance on a needle's point [More,H] |
20766 | Four Noble Truths: life is suffering, caused by attachment, it is avoidable, there is a path [Aho] |