Not so, according to BBC economics correspondent, promoter of bastardy (and daughter of a great man), Stephanie Flanders.
The depression certainly did see a collapse in global trade and capital flows, and a descent into protectionist tariffs and laws. But a fair reading of the evidence suggests these were more the result of the global downturn than the cause.
According to Peter Temin, a distinguished economist at the Massachusetts Institute of Technology, exports were 7% of American GDP in 1929. They fell by 1.5 percentage points in the next two years.
Given the fall in world demand in those years, not all of that fall can be attributed to other countries' retaliation against the US tariffs. And even if it were - overall, GNP over the same period fell by 15%.
So, on any reasonable assumptions, Temin says "the fall in export demand can only be a small part of the story." And, as he points out, even that loss in foreign demand from the tariff would have been partly offset by the fact that the tariff diverted demand from foreign to home-made goods.
His conclusion? "Any net contractionary effect of the tariff was small."
This shouldn't come as a surprise. Even the greatest fans of free trade would admit that the benefits of lower tariffs - or costs of higher ones - are fairly small beer when compared to the kind of collapse in incomes and employment we saw during the depression.
To repeat, I'm not endorsing protectionism, or a policy of "national self-sufficiency" (though intriguingly for his modern admirers, that's what Keynes supported in 1933).
The Keynes piece is fascinating - well worth a read.
Laban's reading a lot of economics blogs at the moment, City Unslicker, Alphaville, Peston. Laban thinks it'll get worse before it gets better - but then he thinks that about everything else !