10 February 2013

Still Say's Law After All These Years

Economics and Politics by Paul Krugman - The Conscience of a ...
When John Maynard Keynes wrote The General Theory, three generations ago, he structured his argument as a refutation of what he called "classical economics", and in particular of Say's Law, the proposition that income must be spent and hence that there can never be an overall deficiency of demand. Ever since, historians of thought have argued about whether this was a fair characterization of what the classical economists, or at any rate his own intellectual opponents, really believed.
Not being an intellectual historian myself, I won't venture an opinion on that subject. What I will say, however, is that Say's Law (Say's false law? Say's fallacy?) is something that opponents of Keynesian economics consistently invoke to this day, falling into exactly the same fallacies Keynes identified back in 1936.
In the past I've caught Brian Riedl and John Cochrane doing it; now Peter Dorman finds Tyler Cowen in their company.
Cowen can't see why corporate hoarding is a problem. Like Riedl and Cochrane, he concedes that there might be some problem if corporations literally piled up stacks of green paper; but he argues that it's completely different if they put the money in a bank, which will lend it out, or use it to buy securities, which can be used to finance someone else's spending.
But of course there isn't any difference. If you put money in a bank, the bank might just accumulate excess reserves. If you buy securities from someone else, the seller might put the cash in his mattress, or put it in a bank that just adds it to its reserves, etc., etc.. The point is that buying goods and services is one thing, adding directly to aggregate demand; buying assets isn't at all the same thing, especially when we're at the zero lower bound.
What's depressing about all this is that Say's Law is a primitive fallacy – so primitive that Keynes has been accused of attacking a straw man. Yet this primitive fallacy, decisively refuted three quarters of a century ago, continues to play a central role in distorting economic discussion and crippling our policy response to depression.