27 ideas
18781 | Inconsistency doesn't prevent us reasoning about some system [Mares] |
18789 | Intuitionist logic looks best as natural deduction [Mares] |
18790 | Intuitionism as natural deduction has no rule for negation [Mares] |
18787 | Three-valued logic is useful for a theory of presupposition [Mares] |
18851 | Pairing (with Extensionality) guarantees an infinity of sets, just from a single element [Rosen] |
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] |
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] |
18782 | The connectives are studied either through model theory or through proof theory [Mares] |
18783 | Many-valued logics lack a natural deduction system [Mares] |
18792 | Situation semantics for logics: not possible worlds, but information in situations [Mares] |
18785 | Consistency is semantic, but non-contradiction is syntactic [Mares] |
18788 | For intuitionists there are not numbers and sets, but processes of counting and collecting [Mares] |
18852 | A Meinongian principle might say that there is an object for any modest class of properties [Rosen] |
18849 | Metaphysical necessity is absolute and universal; metaphysical possibility is very tolerant [Rosen] |
18850 | 'Metaphysical' modality is the one that makes the necessity or contingency of laws of nature interesting [Rosen] |
18858 | Sets, universals and aggregates may be metaphysically necessary in one sense, but not another [Rosen] |
18857 | Standard Metaphysical Necessity: P holds wherever the actual form of the world holds [Rosen] |
18856 | Non-Standard Metaphysical Necessity: when ¬P is incompatible with the nature of things [Rosen] |
18848 | Something may be necessary because of logic, but is that therefore a special sort of necessity? [Rosen] |
18855 | Combinatorial theories of possibility assume the principles of combination don't change across worlds [Rosen] |
18853 | A proposition is 'correctly' conceivable if an ominiscient being could conceive it [Rosen] |
23304 | The ancient Memorists said virtually all types of thinking could be done simply by memory [Sorabji] |
23303 | Stoics say true memory needs reflection and assent, but animals only have perceptual recognition [Sorabji] |
18791 | In 'situation semantics' our main concepts are abstracted from situations [Mares] |
18854 | The MRL view says laws are the theorems of the simplest and strongest account of the world [Rosen] |