13 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] |
| 7071 | Life and rationality are pointless if we can only contemplate the freedom of our own ego [Jacobi] |
| 7072 | Jacobi was the first philosopher to talk of nihilism [Jacobi, by Critchley] |
| 1466 | Claims about God don't seem to claim or deny anything tangible, so evidence is irrelevant [Flew, by PG] |
| 1465 | You can't claim a patch of land is tended by a 'gardener' if there is no evidence, and all counter-evidence is rejected [Flew, by PG] |
| 1467 | Religious people seem unwilling to accept any evidence that God does not love us, so their claim is unfalsifiable [Flew, by PG] |