What Is Money? - NYTimes.com

What Is Money? - NYTimes.com:

...the evils of increasing the money supply.

You hear it all the time: the Fed is printing money! Danger, Will Robinson! In some comments on this blog I see assertions that the true measure of inflation isn’t prices, it’s what happens to the quantity of money.

Now, one thing you might immediately say is that for those who care about, know, actually buying things — you can’t eat money — it’s prices of goods that matter; and for the past three decades, as shown above, there has been remarkably little relationship between the standard monetary aggregates and the inflation rate.

But here’s an even more basic question: what is money, anyway? It’s not a new question, but I think it has become even more pressing in recent years.

Surely we don’t mean to identify money with pieces of green paper bearing portraits of dead presidents. Even Milton Friedman rejected that, more than half a century ago. For one thing, a lot of those pieces of green paper are pretty much inert — sitting outside the United States, in the hoards of drug dealers and such. For another, checking accounts are clearly a close substitute for cash in hand.

Friedman and Schwartz dealt with this by proposing broader aggregates –M1, which adds checking accounts, and M2, which adds a broader range of deposits. And circa 1960 you could argue that those aggregates were good enough.

But now we have a large shadow banking system, in which things like repo serve much the same function as deposits; M3 used to capture some of that, but the Fed discontinued it, in part I think because it wasn’t clear which repo belonged there, and data on repo not involving primary dealers is scattered. Whatever.

The truth is that these days — with credit cards, electronic money, repo, and more all serving the purpose of medium of exchange — it’s not clear that any single number deserves to be called “the” money supply. Intellectually, this isn’t a problem; nor is there necessarily a problem maintaining monetary policy even if there isn’t any single thing you’re willing to call money. Mike Woodford has been writing about this stuff for years.

But if you’re determined to view economic affairs through a sort of paleo-monetarist lens, focused on the evils of “printing money”, you’re going to have a hard time in the modern world, where the definition of money is increasingly vague.