William Easterly has an absolutely bizarre reader survey on his blog:
Please tell me which you think is more probable:
- a country succeeds at economic development, or
- a country succeeds at economic development with a wise and capable leadership.
Since the probability of ‘wise and capable leadership’ is less than 1, the probability of option (2) is P(option 1) x P(wise and capable leadership) < P(option 1). Can this survey tell us about anything other than the mathematical savvy of his readership?
I suppose what it can tell us, if option (2) is preferred, is that making truthful statements (like (1) being more probable than (2)) isn’t always the best way to persuade people that your plan’s a good idea. As Eliezer puts it in explaining the conjunction fallacy:
Adding detail can make a scenario sound more plausible, even though the event necessarily becomes less probable.
So, when you want to persuade people your explanation’s better just add lots of plausible sounding detail to the causality and they’ll think the outcome’s more likely than if you left it out. Words to live by.