40 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] |
| 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] |
| 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] |
| 17757 | Members of ordinals are ordinals, and also subsets of ordinals [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] |
| 13047 | It is knowing 'why' that gives scientific understanding, not knowing 'that' [Salmon] |
| 13065 | Understanding is an extremely vague concept [Salmon] |
| 20769 | Sphaerus he was not assenting to the presence of pomegranates, but that it was 'reasonable' [Sphaerus, by Diog. Laertius] |
| 13054 | Correlations can provide predictions, but only causes can give explanations [Salmon] |
| 13067 | For the instrumentalists there are no scientific explanations [Salmon] |
| 13055 | Good induction needs 'total evidence' - the absence at the time of any undermining evidence [Salmon] |
| 13046 | Scientific explanation is not reducing the unfamiliar to the familiar [Salmon] |
| 13058 | Why-questions can seek evidence as well as explanation [Salmon] |
| 13064 | The three basic conceptions of scientific explanation are modal, epistemic, and ontic [Salmon] |
| 13050 | The 'inferential' conception is that all scientific explanations are arguments [Salmon] |
| 13059 | Ontic explanations can be facts, or reports of facts [Salmon] |
| 13049 | We must distinguish true laws because they (unlike accidental generalizations) explain things [Salmon] |
| 13051 | Deductive-nomological explanations will predict, and their predictions will explain [Salmon] |
| 13053 | A law is not enough for explanation - we need information about what makes a difference [Salmon] |
| 13061 | Flagpoles explain shadows, and not vice versa, because of temporal ordering [Salmon] |
| 13045 | Explanation at the quantum level will probably be by entirely new mechanisms [Salmon] |
| 13062 | Does an item have a function the first time it occurs? [Salmon] |
| 13063 | Explanations reveal the mechanisms which produce the facts [Salmon] |
| 13060 | Can events whose probabilities are low be explained? [Salmon] |
| 13056 | Statistical explanation needs relevance, not high probability [Salmon] |
| 13057 | Think of probabilities in terms of propensities rather than frequencies [Salmon] |