I agree with both of you. We can't 100% argue that the prevailing wisdom is infallible because of real examples of the opposite occurring rarely, like the ulcer

I agree with both of you. We can't 100% argue that the prevailing wisdom is infallible because of real examples of the opposite occurring rarely, like the ulcer case. However, on the balance I prefer to go with prevailing wisdom. It's a judgement call that requires a human to detail with probabilities and humans are very bad at probabilities.