Never say never

The VOA reports:

Blanchard and his IMF colleagues say there is no chance of a repeat of the global depression of the 1930s, because the lessons of that painful decade have been learned.

Is Olivier really this confident? I, too, would bet against another Great Depression. In fact, in my personal portfolio, I am. But "no chance" seems a bit of an overstatement, especially since there is not a consensus among economists about why the Great Depression was as bad as it was. In other words, the economics profession has not confidently established what the lessons from that painful decade were. If we are not sure what we have learned from history, how can we be sure not to repeat it?