Thinking books · Logic & argumentation · David Kelley, 1988

The Art of Reasoning — the big ideas

A full introduction to reasoning: concepts, definitions, deduction, induction and fallacies.

Free — no account needed to read

The big ideas

It starts with definitions rather than arguments, on the grounds that most disputes are about what a word covers, and that a definition has to be tested against cases it should and should not include.

It separates validity from truth explicitly: an argument can be perfectly valid and lead to a false conclusion, because validity is only about whether the conclusion follows.

Analysing an argument means putting it in standard form — premises listed, conclusion stated — which makes hidden premises visible almost immediately.

Practise it — no need to have read it

Take an argument you made this week. Write it as: because A, and because B, therefore C. Then list what must also be true for C to follow.

A hint: The things you had to add are the hidden premises. They are usually where it breaks.

Where it shows up in real life

• Written proposals
• Disagreements at work
• Checking your own reasoning

Described in our own words with the source named — never quoted, and not a substitute for reading the book.