45 ideas
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] |
18680 | To avoid misunderstandings supervenience is often expressed negatively: no A-change without B-change [Orsi] |
14508 | A 'thisness' is a thing's property of being identical with itself (not the possession of self-identity) [Adams,RM] |
14511 | There are cases where mere qualities would not ensure an intrinsic identity [Adams,RM] |
12031 | Essences are taken to be qualitative properties [Adams,RM] |
12034 | If the universe was cyclical, totally indiscernible events might occur from time to time [Adams,RM] |
14510 | Two events might be indiscernible yet distinct, if there was a universe cyclical in time [Adams,RM] |
16455 | Black's two globes might be one globe in highly curved space [Adams,RM] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
14507 | Are possible worlds just qualities, or do they include primitive identities as well? [Adams,RM] |
11964 | Possible worlds are world-stories, maximal descriptions of whole non-existent worlds [Adams,RM, by Molnar] |
16451 | Adams says anti-haecceitism reduces all thisness to suchness [Adams,RM, by Stalnaker] |
11901 | Haecceitism may or may not involve some logical connection to essence [Adams,RM, by Mackie,P] |
14512 | Moderate Haecceitism says transworld identities are primitive, but connected to qualities [Adams,RM] |
12032 | Direct reference is by proper names, or indexicals, or referential uses of descriptions [Adams,RM] |
18684 | Rather than requiring an action, a reason may 'entice' us, or be 'eligible', or 'justify' it [Orsi] |
18666 | Value-maker concepts (such as courageous or elegant) simultaneously describe and evaluate [Orsi] |
18685 | Final value is favoured for its own sake, and personal value for someone's sake [Orsi] |
18667 | The '-able' concepts (like enviable) say this thing deserves a particular response [Orsi] |
18679 | Things are only valuable if something makes it valuable, and we can ask for the reason [Orsi] |
18682 | A complex value is not just the sum of the values of the parts [Orsi] |
18683 | Trichotomy Thesis: comparable values must be better, worse or the same [Orsi] |
18686 | The Fitting Attitude view says values are fitting or reasonable, and values are just byproducts [Orsi] |
18672 | Values from reasons has the 'wrong kind of reason' problem - admiration arising from fear [Orsi] |
18677 | A thing may have final value, which is still derived from other values, or from relations [Orsi] |
18669 | Values can be normative in the Fitting Attitude account, where 'good' means fitting favouring [Orsi] |
18670 | The Buck-Passing view of normative values says other properties are reasons for the value [Orsi] |
18668 | Truths about value entail normative truths about actions or attitudes [Orsi] |