7 ms·

Pop-science articles about quantum mechanics make this fallacy (affirming the consequent) all the time. Them: "PilotWave implies E. E was observed. Therefore P

• Jach 10y ago
  This is how common sense works, though, and is covered formally by probability theory. I'd also argue science works by probability theory more so than deductive logic, so you're only right that this isn't how logic works.
  • cousin_it 10y ago
    Probability theory doesn't work that way either. If A and B both imply C, then seeing C doesn't raise the probability of A compared to B.
  • Strilanc 10y ago
    Actually, this issue also applies to probability theory. It does get more subtle, though, because theories might predict observations with differing probabilities and what matters is the difference in probabilities. But this this case theory A and theory B both predict observation C with the same probability p. So you gain 0 decibels of evidence (w.r.t A-vs-B) whether or not you observe C. When I said "You're missing the 'not-PilotWave implies not-E' part!", I was making a simplified reference to the fact that the probabilities predicted by not-PilotWave (e.g. Copenhagen) need to be different from the probabilities predicted by PilotWave in order for evidence/inference to pry them apart. See [1] if that all sounded confusing. 1: http://www.yudkowsky.net/rational/technical/ http://www.yudkowsky.net/rational/technical/