There’s been even more ink spilled lately than usual over the reasons monetary policy seems to have lost its mojo, and what it would take to get it back. Admittedly a lot of it is the same dueling pronouncements over whether helicopter money must always or can never work, but with the volume turned up a notch.
From my point of view, the conceptual issues here are simpler than you’d guess from the shouting. It comes down to two questions. First, how much control does the central bank have over the terms on which various economic units can adjust their balance sheets by selling assets or issuing new liabilities? And second, how many units would increase their spending on goods and services if they could more easily make the required balance sheet adjustments? Obviously, these questions are not straightforward. And they have to be answered jointly — to be effective, monetary policy has to reach not just the elasticity of the financial system in general, but its elasticity at the points where it meets financially-constrained units. But in principle, it’s simple enough.
The whole question, it seems to me, is made more confusing than it needs to be by two bad habits of economists. First is the tendency to think of the economy as a tightly articulated system, with just a few degrees of freedom. (This is one way of describing the focus on equilibrium.) To an economist, the economy is like a pool of water, where a disturbance to any part of it leads to a rapid adjustment of the whole system to a final state that can be described on the basis of a few parameters, without any information about specific components. What’s the alternative? The economy is like a pile of rocks: Disturbances may remain local rather than being transmitted to the whole system; less information about the structure can be derived from a few global parameters and more depends on the contingent states of the individual components; and stability is the result not of rapid adjustment, but rather of buffers that make adjustment unnecessary. Economists’ fixation on tightly-articulated systems tempts us to think about a single parameter (the interest rate, the money supply) changing uniformly through the economy (and often over all of time), and economic units fully adjusting their behavior in response. It leads to a focus on the ultimate endpoint of an adjustment process rather than its next step. This yields stronger, and often paradoxical, conclusions than you would reach if you imagined beliefs and behavior changing locally and incrementally.
The second vice is economists’ incorrigible tendency to mistake the map for the territory. Like the first, this leads us to overvalue formal logical analysis at the expense of the concrete and historical. It also leads us to take an abstract representation that was adopted to clarify a particular question in a particular context, and treat it as an object in itself, as if it descried a self-contained world. Anyone who’s spent time around economists will have noticed their habit of regarding any label on a variable in an equation, as a physical object out there in the world. There’s nothing wrong — it should go without saying — with formal, logical analysis; as Marx said, abstraction is the social scientist’s equivalent of the microscope or telescope. The difference is that economists treat models as toy train sets rather than as tools. In the case of monetary policy, it works like this. The central bank adopts a policy tool which, in the institutional context at the time, gives them adequate control over the overall pace of credit expansion. Economists abstract from the — genuinely, but only for the moment — irrelevant details of exactly how this instrument works, and postulate a direct connection with the economic outcome it is meant to control. To make communication with other economists easier, they often also construct a model where just exactly the intervention carried out by the central bank is what’s needed to restore the Walrasian optimum. This may be harmless enough as long as the policy framework persists. But the dogmatic insistence that “the central bank sets the money supply” or “the central bank sets the interest rate” is a source of endless confusion when the instrument is changing to something else.
So coming back to the concrete situation, how much can the Fed influence the expansion of bank balance sheets, and how much is expenditure on current production held down by the inelasticity of bank balance sheets? In the idealized financial world of circa 1950, the answer was simple. Commercial bank liabilities were deposits; deposits expanded through investment loans to business and households; and the total volume of deposits was strictly limited by the reserves made available by the Fed. The situation today is more complicated. But we have a better chance of making sense of it if we don’t get distracted by brain teasers about “M”.
I wrote this a month or two ago and didn’t post it for some reason. As a critical post, it really ought to have links to examples of the positions being criticized; but at this point it doesn’t seem worth the trouble.