I don't think that answers mikeash's question. He is not talking about always being wrong. He is pointing out that the incentives are not symmetric. If you say

I don't think that answers mikeash's question. He is not talking about always being wrong. He is pointing out that the incentives are not symmetric. If you say that you are 100% certain, and you are wrong, then you fail the class. If the incentives were symmetric, if you said you were 100% certain and you were correct, then you would automatically pass the class. A potential answer is: this asymmetry is similar to incentives outside the classroom. Claiming 100% certainty and being wrong can be disastrous to your reputation, and likely much more negative than the positive benefits of claiming 100% certainty and being correct.