MEPX
Chapter 4 of 11All chapters
  1. 1How puzzles trick you
  2. 2All, some and none
  3. 3If, then
  4. 4Common fallacies
  5. 5Number sequences
  6. 6Words into equations
  7. 7Rate and work problems
  8. 8Elimination grids
  9. 9Knights, knaves and self reference
  10. 10Reading exactly
  11. 11Building the habit

Chapter 4 of 11

Common fallacies

Named mistakes are easier to spot.

The frequent ones

Affirming the consequent reads a rule backwards. Denying the antecedent assumes that no P means no Q. Both feel natural and both are wrong.

  • Correlation is not causation, and a third cause explains many pairs.
  • Survivorship bias looks only at what made it through.

Base rates

A test that is 99 percent accurate for a condition that one person in ten thousand has still produces mostly false positives. Ignoring how rare something is beforehand is the most expensive error in this list.