When I was in college, I overheard two senior faculty arguing over an undergraduate probability homework assignment. This seemed very strange. It occurred to me that I’d never seen faculty argue over something elementary before, and I couldn’t imagine an argument over, say, a calculus homework problem. Professors might forget how to do a calculus problem, or make a mistake in a calculation, but you wouldn’t see two professors defending incompatible solutions.
Intuitive discussions of probability are very likely to be wrong. Experts know this. They’ll say things like “I imagine the answer is around this, but I’d have to go through the calculations to be sure.” Probability is not like physics where you can usually get within an order of magnitude of a correct answer without formal calculation. Probabilistic intuition doesn’t take you as far as physical intuition.
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