Matt Yglesias argues that Hitler was massively irrational not to keep his word and not invade Poland.

Is the conservative view that, in general, when you offer foreign countries a deal that they rationally ought to accept they will, as a general matter, usually back out of the deal even though doing so will have disastrous consequences for them? That can’t be right. At the end of the day, the reason analogies to World War II strike people so vividly is that they were so unusual. You can’t base your everyday decision-making on an extreme historical outlier.

First, just because you lose a gamble doesn’t mean its wasn’t worth taking.

Second, I think the conservative point is that you can’t trust dictators to be rational. They are crazy by nature and must be defeated.