18 ideas
| 343 | The unexamined life is not worth living for men [Socrates] |
| 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] |
| 13007 | Archimedes defined a straight line as the shortest distance between two points [Archimedes, by Leibniz] |
| 339 | Men fear death as a great evil when it may be a great blessing [Socrates] |
| 344 | If death is like a night of dreamless sleep, such nights are very pleasant [Socrates] |
| 2 | We should not even harm someone who harms us [Socrates] |
| 345 | A good man cannot be harmed, either in life or in death [Socrates] |
| 346 | One ought not to return a wrong or injury to any person, whatever the provocation [Socrates] |
| 341 | Wealth is good if it is accompanied by virtue [Socrates] |
| 347 | Will I stand up against the law, simply because I have been unjustly judged? [Socrates] |
| 338 | Socrates is accused of denying the gods, saying sun is stone and moon is earth [Socrates, by Plato] |