Thinking books · Scientific thinking · Carl Sagan, 1995
The Demon-Haunted World — the big ideas
A defence of scientific thinking as a way of staying honest, not just a way of doing science.
Free — no account needed to read
The big ideas
It offers a baloney detection kit: independent confirmation, debate, quantification where possible, multiple hypotheses, and not being attached to a hypothesis because it is yours.
The dragon in the garage: a claim arranged so that no test could ever detect it is not a modest claim but an empty one.
It holds two things together deliberately — openness to new ideas and rigorous scepticism — and argues that either alone is useless.
Extraordinary claims requiring extraordinary evidence is a statement about proportion, not a way of dismissing things.
Practise it — no need to have read it
Take a claim you believe that you have never tested. Write what observation would show it false. If you cannot name one, note that plainly.
A hint: Unfalsifiable does not mean untrue. It means do not treat it as a finding.
Where it shows up in real life
- Health claims
- Business advice
- Your own theories about why something is happening
Described in our own words with the source named — never quoted, and not a substitute for reading the book.
Thinking methods from this book
- State what would refute it — Testing whether a claim is the kind of thing evidence could ever settle.
- The six-question claim check — A fixed pass over any claim before you act on it.
The thinking it builds
- Critical Thinking — Evaluate claims and evidence
- Logical Thinking — Reason consistently