Combining Texts

All the ideas for 'Necessary Existents', 'Reference and Essence (1st edn)' and 'Negation'

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21 ideas

2. Reason / A. Nature of Reason / 9. Limits of Reason
18781 Inconsistency doesn't prevent us reasoning about some system [Mares]
2. Reason / D. Definition / 11. Ostensive Definition
18889 Ostensive definitions needn't involve pointing, but must refer to something specific [Salmon,N]
4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / h. System S5
14627 S4, and therefore S5, are invalid for metaphysical modality [Salmon,N, by Williamson]
4. Formal Logic / E. Nonclassical Logics / 2. Intuitionist Logic
18789 Intuitionist logic looks best as natural deduction [Mares]
18790 Intuitionism as natural deduction has no rule for negation [Mares]
4. Formal Logic / E. Nonclassical Logics / 3. Many-Valued Logic
18787 Three-valued logic is useful for a theory of presupposition [Mares]
5. Theory of Logic / A. Overview of Logic / 6. Classical Logic
18793 Material implication (and classical logic) considers nothing but truth values for implications [Mares]
18784 In classical logic the connectives can be related elegantly, as in De Morgan's laws [Mares]
5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
18786 Excluded middle standardly implies bivalence; attacks use non-contradiction, De M 3, or double negation [Mares]
18780 Standard disjunction and negation force us to accept the principle of bivalence [Mares]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
18782 The connectives are studied either through model theory or through proof theory [Mares]
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
18783 Many-valued logics lack a natural deduction system [Mares]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
18792 Situation semantics for logics: not possible worlds, but information in situations [Mares]
5. Theory of Logic / K. Features of Logics / 2. Consistency
18785 Consistency is semantic, but non-contradiction is syntactic [Mares]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / b. Intuitionism
18788 For intuitionists there are not numbers and sets, but processes of counting and collecting [Mares]
9. Objects / D. Essence of Objects / 7. Essence and Necessity / a. Essence as necessary properties
18888 Essentialism says some properties must be possessed, if a thing is to exist [Salmon,N]
19. Language / B. Reference / 1. Reference theories
18886 Frege's 'sense' solves four tricky puzzles [Salmon,N]
19. Language / B. Reference / 3. Direct Reference / a. Direct reference
18887 The perfect case of direct reference is a variable which has been assigned a value [Salmon,N]
19. Language / C. Assigning Meanings / 2. Semantics
18791 In 'situation semantics' our main concepts are abstracted from situations [Mares]
19. Language / D. Propositions / 3. Concrete Propositions
19216 Propositions (such as 'that dog is barking') only exist if their items exist [Williamson]
26. Natural Theory / B. Natural Kinds / 5. Reference to Natural Kinds
18891 Nothing in the direct theory of reference blocks anti-essentialism; water structure might have been different [Salmon,N]