15 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] |
| 12066 | Aristotelian and Kripkean essentialism are very different theories [Witt] |
| 12067 | An Aristotelian essence is a nonlinguistic correlate of the definition [Witt] |
| 12082 | If unity is a matter of degree, then essence may also be a matter of degree [Witt] |
| 12089 | Essences mainly explain the existence of unified substance [Witt] |
| 12102 | Essential properties of origin are too radically individual for an Aristotelian essence [Witt] |
| 5880 | Xenocrates held that the soul had no form or substance, but was number [Xenocrates, by Cicero] |
| 12085 | Reality is directional [Witt] |