From the Stoic logic of Chrysippus (3rd century BCE), recast by George Boole (1847) and Gottlob Frege (1879), and given modern form by Alfred North Whitehead and Bertrand Russell (Principia Mathematica, 1910).
Reduces an argument to lettered statements joined by and, or, not, and if-then, then checks whether the conclusion follows from that structure alone.
When to reach for it
A contract clause, policy chain, or eligibility rule that must be shown to hold whatever its terms mean.
How it runs
- Break the argument into simple true-or-false statements.
- Give each statement a letter.
- Rewrite the premises and conclusion with and, or, not, and if-then.
- Build a truth table or apply standard inference rules.
- Find any row where the premises hold and the conclusion fails.
Where it sits in SOLVE eX
- Any step: Tools that serve every step: habits of thought and checks on the thinking itself.
Go to the source
- Stoic propositional logic, 3rd century BCE
- The Mathematical Analysis of Logic, 1847
- Begriffsschrift, 1879
- Principia Mathematica, 1910