logic
- Gödel's Incompleteness Theorems: What They Prove
Gödel's incompleteness theorems show that no consistent formal system for basic arithmetic can prove every truth about numbers, or prove its own consistency. - Logical Fallacies
Common errors in reasoning — formal and informal — with the standard catalogue and its caveats. - Modus Ponens and Modus Tollens
The two most basic valid forms of conditional reasoning, and the fallacies that mimic them.