What would a new macroeconomics look like?

Dec 9 JDN 2458462

In previous posts I have extensively criticized the current paradigm of macroeconomics. But it’s always easier to tear the old edifice down than to build a better one in its place. So in this post I thought I’d try to be more constructive: What sort of new directions could macroeconomics take?

The most important change we need to make is to abandon the assumption of dynamic optimization. This will be a very hard sell, as most macroeconomists have become convinced that the Lucas Critique means we need to always base everything on the dynamic optimization of a single representative agent. I don’t think this was actually what Lucas meant (though maybe we should ask him; he’s still at Chicago), and I certainly don’t think it is what he should have meant. He had a legitimate point about the way macroeconomics was operating at that time: It was ignoring the feedback loops that occur when we start trying to change policies.

Goodhart’s Law is probably a better formulation: Once you make an indicator into a target, you make it less effective as an indicator. So while inflation does seem to be negatively correlated with unemployment, that doesn’t mean we should try to increase inflation to extreme levels in order to get rid of unemployment; sooner or later the economy is going to adapt and we’ll just have both inflation and unemployment at the same time. (Campbell’s Law provides a specific example that I wish more people in the US understood: Test scores would be a good measure of education if we didn’t use them to target educational resources.)

The reason we must get rid of dynamic optimization is quite simple: No one behaves that way.

It’s often computationally intractable even in our wildly oversimplified models that experts spend years working onnow you’re imagining that everyone does this constantly?

The most fundamental part of almost every DSGE model is the Euler equation; this equation comes directly from the dynamic optimization. It’s supposed to predict how people will choose to spend and save based upon their plans for an infinite sequence of future income and spending—and if this sounds utterly impossible, that’s because it is. Euler equations don’t fit the data at all, and even extreme attempts to save them by adding a proliferation of additional terms have failed. (It reminds me very much of the epicycles that astronomers used to add to the geocentric model of the universe to try to squeeze in weird results like Mars, before they had the heliocentric model.)

We should instead start over: How do people actually choose their spending? Well, first of all, it’s not completely rational. But it’s also not totally random. People spend on necessities before luxuries; they try to live within their means; they shop for bargains. There is a great deal of data from behavioral economics that could be brought to bear on understanding the actual heuristics people use in deciding how to spend and save. There have already been successful policy interventions using this knowledge, like Save More Tomorrow.

The best thing about this is that it should make our models simpler. We’re no longer asking each agent in the model to solve an impossible problem. However people actually make these decisions, we know it can be done, because it is being done. Most people don’t really think that hard, even when they probably should; so the heuristics really can’t be that complicated. My guess is that you can get a good fit—certainly better than an Euler equation—just by assuming that people set a target for how much they’re going to save (which is also probably pretty small for most people), and then spend the rest.

The second most important thing we need to add is inequality. Some people are much richer than others; this is a very important fact about economics that we need to understand. Yet it has taken the economics profession decades to figure this out, and even now I’m only aware of one class of macroeconomic models that seriously involves inequality, the Heterogeneous Agent New Keynesian (HANK) models which didn’t emerge until the last few years (the earliest publication I can find is 2016!). And these models are monsters; they are almost always computationally intractable and have a huge number of parameters to estimate.

Understanding inequality will require more parameters, that much is true. But if we abandon dynamic optimization, we won’t need as many as the HANK models have, and most of the new parameters are actually things we can observe, like the distribution of wages and years of schooling.

Observability of parameters is a big deal. Another problem with the way the Lucas Critique has been used is that we’ve been told we need to be using “deep structural parameters” like the temporal elasticity of substitution and the coefficient of relative risk aversion—but we have no idea what those actually are. We can’t observe them, and all of our attempts to measure them indirectly have yielded inconclusive or even inconsistent results. This is probably because these parameters are based on assumptions about human rationality that are simply not realistic. Most people probably don’t have a well-defined temporal elasticity of substitution, because their day-to-day decisions simply aren’t consistent enough over time for that to make sense. Sometimes they eat salad and exercise; sometimes they loaf on the couch and drink milkshakes. Likewise with risk aversion: many moons ago I wrote about how people will buy both insurance and lottery tickets, which no one with a consistent coefficient of relative risk aversion would ever do.

So if we are interested in deep structural parameters, we need to base those parameters on behavioral experiments so that we can understand actual human behavior. And frankly I don’t think we need deep structural parameters; I think this is a form of greedy reductionism, where we assume that the way to understand something is always to look at smaller pieces. Sometimes the whole is more than the sum of its parts. Economists obviously feel a lot of envy for physics; but they don’t seem to understand that aerodynamics would never have (ahem) gotten off the ground if we had first waited for an exact quantum mechanical solution of the oxygen atom (which we still don’t have, by the way). Macroeconomics may not actually need “microfoundations” in the strong sense that most economists intend; it needs to be consistent with small-scale behavior, but it doesn’t need to be derived from small-scale behavior.

This means that the new paradigm in macroeconomics does not need to be computationally intractable. Using heuristics instead of dynamic optimization and worrying less about microfoundations will make the models simpler; adding inequality need not make them so much more complicated.

Fighting the zero-sum paradigm

Dec 2 JDN 2458455

It should be obvious at this point that there are deep, perhaps even fundamental, divides between the attitudes and beliefs of different political factions. It can be very difficult to even understand, much less sympathize, with the concerns of people who are racist, misogynistic, homophobic, xenophobic, and authoritarian.
But at the end of the day we still have to live in the same country as these people, so we’d better try to understand how they think. And maybe, just maybe, that understanding will help us to change them.

There is one fundamental belief system that I believe underlies almost all forms of extremism. Right now right-wing extremism is the major threat to global democracy, but left-wing extremism subscribes to the same core paradigm (consistent with Horseshoe Theory).

I think the best term for this is the zero-sum paradigm. The idea is quite simple: There is a certain amount of valuable “stuff” (money, goods, land, status, happiness) in the world, and the only political question is who gets how much.

Thus, any improvement in anyone’s life must, necessarily, come at someone else’s expense. If I become richer, you become poorer. If I become stronger, you become weaker. Any improvement in my standard of living is a threat to your status.

If this belief were true, it would justify, or at least rationalize, all sorts of destructive behavior: Any harm I can inflict upon someone else will yield a benefit for me, by some fundamental conservation law of the universe.

Viewed in this light, beliefs like patriarchy and White supremacy suddenly become much more comprehensible: Why would you want to spend so much effort hurting women and Black people? Because, by the fundamental law of zero-sum, any harm to women is a benefit to men, and any harm to Black people is a benefit to White people. The world is made of “teams”, and you are fighting for your own against all the others.

And I can even see why such an attitude is seductive: It’s simple and easy to understand. And there are many circumstances where it can be approximately true.
When you are bargaining with your boss over a wage, one dollar more for you is one dollar less for your boss.
When your factory outsources production to China, one more job for China is one less job for you.

When we vote for President, one more vote for the Democrats is one less vote for the Republicans.

But of course the world is not actually zero-sum. Both you and your boss would be worse off if your job were to disappear; they need your work and you need their money. For every job that is outsourced to China, another job is created in the United States. And democracy itself is such a profound public good that it basically overwhelms all others.

In fact, it is precisely when a system is running well that the zero-sum paradigm becomes closest to true. In the space of all possible allocations, it is the efficient ones that behave in something like a zero-sum way, because when the system is efficient, we are already producing as much as we can.

This may be part of why populist extremism always seems to assert itself during periods of global prosperity, as in the 1920s and today: It is precisely when the world is running at its full capacity that it feels most like someone else’s gain must come at your loss.

Yet if we live according to the zero-sum paradigm, we will rapidly destroy the prosperity that made that paradigm seem plausible. A trade war between the US and China would put millions out of work in both countries. A real war with conventional weapons would kill millions. A nuclear war would kill billions.

This is what we must convey: We must show people just how good things are right now.

This is not an easy task; when people want to believe the world is falling apart, they can very easily find excuses to do so. You can point to the statistics showing a global decline in homicide, but one dramatic shooting on the TV news will wipe that all away. You can show the worldwide rise in real incomes across the board, but that won’t console someone who just lost their job and blames outsourcing or immigrants.

Indeed, many people will be offended by the attempt—the mere suggestion that the world is actually in very good shape and overall getting better will be perceived as an attempt to deny or dismiss the problems and injustices that still exist.

I encounter this especially from the left: Simply pointing out the objective fact that the wealth gap between White and Black households is slowly closing is often taken as a claim that racism no longer exists or doesn’t matter. Congratulating the meteoric rise in women’s empowerment around the world is often paradoxically viewed as dismissing feminism instead of lauding it.

I think the best case against progress can be made with regard to global climate change: Carbon emissions are not falling nearly fast enough, and the world is getting closer to the brink of truly catastrophic ecological damage. Yet even here the zero-sum paradigm is clearly holding us back; workers in fossil-fuel industries think that the only way to reduce carbon emissions is to make their families suffer, but that’s simply not true. We can make them better off too.

Talking about injustice feels righteous. Talking about progress doesn’t. Yet I think what the world needs most right now—the one thing that might actually pull us back from the brink of fascism or even war—is people talking about progress.

If people think that the world is full of failure and suffering and injustice, they will want to tear down the whole system and start over with something else. In a world that is largely democratic, that very likely means switching to authoritarianism. If people think that this is as bad as it gets, they will be willing to accept or even instigate violence in order to change to almost anything else.

But if people realize that in fact the world is full of success and prosperity and progress, that things are right now quite literally better in almost every way for almost every person in almost every country than they were a hundred—or even fifty—years ago, they will not be so eager to tear the system down and start anew. Centrism is often mocked (partly because it is confused with false equivalence), but in a world where life is improving this quickly for this many people, “stay the course” sounds awfully attractive to me.
That doesn’t mean we should ignore the real problems and injustices that still exist, of course. There is still a great deal of progress left to be made.  But I believe we are more likely to make progress if we acknowledge and seek to continue the progress we have already made, than if we allow ourselves to fall into despair as if that progress did not exist.