33 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] |
4568 | If 'Queen of England' does not refer if there is no queen, its meaning can't refer if there is one [Cooper,DE] |
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] |
4574 | If some peoples do not have categories like time or cause, they can't be essential features of rationality [Cooper,DE] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
4573 | If it is claimed that language correlates with culture, we must be able to identify the two independently [Cooper,DE] |
4575 | A person's language doesn't prove their concepts, but how are concepts deduced apart from language? [Cooper,DE] |
4561 | Many sentences set up dispositions which are irrelevant to the meanings of the sentences [Cooper,DE] |
4564 | I can meaningfully speculate that humans may have experiences currently impossible for us [Cooper,DE] |
4565 | The verification principle itself seems neither analytic nor verifiable [Cooper,DE] |
4563 | 'How now brown cow?' is used for elocution, but this says nothing about its meaning [Cooper,DE] |
4562 | Most people know how to use the word "Amen", but they do not know what it means [Cooper,DE] |
4571 | Reference need not be a hit-or-miss affair [Cooper,DE] |
4566 | Any thesis about reference is also a thesis about what exists to be referred to [Cooper,DE] |
4572 | If predicates name things, that reduces every sentence to a mere list of names [Cooper,DE] |
4576 | An analytic truth is one which becomes a logical truth when some synonyms have been replaced [Cooper,DE] |
19739 | The maxim for suicide is committed to the value of life, and is thus contradictory [Kant] |