19 ideas
13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward] |
13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts [Engelbretsen/Sayward] |
13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences [Engelbretsen/Sayward] |
13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward] |
13850 | In modern logic all formal validity can be characterised syntactically [Engelbretsen/Sayward] |
13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward] |
13851 | Unlike most other signs, = cannot be eliminated [Engelbretsen/Sayward] |
13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
16014 | It is controversial whether only 'numerical identity' allows two things to be counted as one [Noonan] |
16024 | I could have died at five, but the summation of my adult stages could not [Noonan] |
16023 | Stage theorists accept four-dimensionalism, but call each stage a whole object [Noonan] |
16015 | Problems about identity can't even be formulated without the concept of identity [Noonan] |
16017 | Identity is usually defined as the equivalence relation satisfying Leibniz's Law [Noonan] |
16016 | Identity definitions (such as self-identity, or the smallest equivalence relation) are usually circular [Noonan] |
16020 | Identity can only be characterised in a second-order language [Noonan] |
16018 | Indiscernibility is basic to our understanding of identity and distinctness [Noonan] |
16019 | Leibniz's Law must be kept separate from the substitutivity principle [Noonan] |
13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |