30 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] |
23664 | Powers are quite distinct and simple, and so cannot be defined [Reid] |
23669 | Thinkers say that matter has intrinsic powers, but is also passive and acted upon [Reid] |
23666 | It is obvious that there could not be a power without a subject which possesses it [Reid] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
23665 | Consciousness is the power of mind to know itself, and minds are grounded in powers [Reid] |
23668 | Our own nature attributes free determinations to our own will [Reid] |
14080 | Are causal descriptions part of the causal theory of reference, or are they just metasemantic? [Kaplan, by Schaffer,J] |
20051 | Reid said that agent causation is a unique type of causation [Reid, by Stout,R] |
8383 | Day and night are constantly conjoined, but they don't cause one another [Reid, by Crane] |
23667 | Regular events don't imply a cause, without an innate conviction of universal causation [Reid] |
23670 | Scientists don't know the cause of magnetism, and only discover its regulations [Reid] |
23671 | Laws are rules for effects, but these need a cause; rules of navigation don't navigate [Reid] |