34 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] |
14347 | A 'finkish' disposition is one that is lost immediately after the appropriate stimulus [Corry] |
14348 | An 'antidote' allows a manifestation to begin, but then blocks it [Corry] |
14350 | If a disposition is never instantiated, it shouldn't be part of our theory of nature [Corry] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
14351 | Maybe an experiment unmasks an essential disposition, and reveals its regularities [Corry] |
7621 | Special relativity, unlike general relativity, was operationalist in spirit [Putnam on Einstein] |
22955 | Einstein took causation to be the bedrock of physics [Einstein, by Coveney/Highfield] |
20638 | General relativity assumes laws of nature are the same in all frames of reference [Einstein, by Close] |
14346 | Dispositional essentialism says fundamental laws of nature are strict, not ceteris paribus [Corry] |
20636 | Newton is a special case of Einstein's general theory, with an infinite speed of light [Einstein, by Close] |
21230 | The theory is 'special' because it sticks to observers moving straight, at constant speeds [Einstein, by Farmelo] |
21231 | Assume the speed of light is constant for all observers, and the laws of physics are the same [Einstein, by Farmelo] |
20634 | General Relativity says there is no absolute force or acceleration [Einstein, by Close] |
20648 | Mass is a measure of energy content [Einstein] |
21232 | Space-time arises from the connection between measurements of space and of time [Einstein, by Farmelo] |
7626 | I do not believe in a personal God [Einstein] |