40 ideas
18781 | Inconsistency doesn't prevent us reasoning about some system [Mares] |
10170 | While true-in-a-model seems relative, true-in-all-models seems not to be [Reck/Price] |
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] |
10166 | ZFC set theory has only 'pure' sets, without 'urelements' [Reck/Price] |
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] |
18780 | Standard disjunction and negation force us to accept the principle of bivalence [Mares] |
18786 | Excluded middle standardly implies bivalence; attacks use non-contradiction, De M 3, or double negation [Mares] |
18782 | The connectives are studied either through model theory or through proof theory [Mares] |
10175 | Three types of variable in second-order logic, for objects, functions, and predicates/sets [Reck/Price] |
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] |
10165 | 'Analysis' is the theory of the real numbers [Reck/Price] |
10174 | Mereological arithmetic needs infinite objects, and function definitions [Reck/Price] |
10164 | Peano Arithmetic can have three second-order axioms, plus '1' and 'successor' [Reck/Price] |
10172 | Set-theory gives a unified and an explicit basis for mathematics [Reck/Price] |
10167 | Structuralism emerged from abstract algebra, axioms, and set theory and its structures [Reck/Price] |
10169 | Relativist Structuralism just stipulates one successful model as its arithmetic [Reck/Price] |
10179 | There are 'particular' structures, and 'universal' structures (what the former have in common) [Reck/Price] |
10181 | Pattern Structuralism studies what isomorphic arithmetic models have in common [Reck/Price] |
10182 | There are Formalist, Relativist, Universalist and Pattern structuralism [Reck/Price] |
10168 | Formalist Structuralism says the ontology is vacuous, or formal, or inference relations [Reck/Price] |
10178 | Maybe we should talk of an infinity of 'possible' objects, to avoid arithmetic being vacuous [Reck/Price] |
10176 | Universalist Structuralism is based on generalised if-then claims, not one particular model [Reck/Price] |
10177 | Universalist Structuralism eliminates the base element, as a variable, which is then quantified out [Reck/Price] |
10171 | The existence of an infinite set is assumed by Relativist Structuralism [Reck/Price] |
18788 | For intuitionists there are not numbers and sets, but processes of counting and collecting [Mares] |
10173 | A nominalist might avoid abstract objects by just appealing to mereological sums [Reck/Price] |
18791 | In 'situation semantics' our main concepts are abstracted from situations [Mares] |
7590 | Consequentialism emphasises value rather than obligation in morality [Scruton] |
7589 | Altruism is either emotional (where your interests are mine) or moral (where they are reasons for me) [Scruton] |
7595 | The idea of a right seems fairly basic; justice may be the disposition to accord rights to people [Scruton] |
7588 | Allegiance is fundamental to the conservative view of society [Scruton] |
7594 | Democrats are committed to a belief and to its opposite, if the majority prefer the latter [Scruton] |
7593 | Liberals focus on universal human freedom, natural rights, and tolerance [Scruton, by PG] |
7592 | For positivists law is a matter of form, for naturalists it is a matter of content [Scruton] |
7587 | The issue of abortion seems insoluble, because there is nothing with which to compare it [Scruton] |