14 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] |
| 17423 | The essence of natural numbers must reflect all the functions they perform [Sicha] |
| 17424 | Counting puts an initial segment of a serial ordering 1-1 with some other entities [Sicha] |
| 17425 | To know how many, you need a numerical quantifier, as well as equinumerosity [Sicha] |
| 18528 | The single imagined 'interval' between things only exists in the intellect [Auriol] |
| 16589 | Prime matter lacks essence, but is only potentially and indeterminately a physical thing [Auriol] |
| 16651 | God can do anything non-contradictory, as making straightness with no line, or lightness with no parts [Auriol] |