What’s Wrong With Modern Macro?

After 15 posts, 17,795 words, and about 9 months, my series of posts on the problems with modern macro is finally complete. If anyone cares, here is the list of all the posts in order.

Part 1: Before Modern Macro – Keynesian Economics

Part 2: The Death of Keynesian Economics: The Lucas Critique, Microfoundations, and Rational Expectations

Part 3: Real Business Cycle and the Birth of DSGE Models

Part 4: How Did a “Measure of our Ignorance” Become the Cause of Business Cycles?

Part 5: Filtering Away All Our Problems

Part 6: The Illusion of Microfoundations I: The Aggregate Production Function

Part 7: The Illusion of Microfoundations II: The Representative Agent

Part 8: Rational Expectations Aren’t so Rational

Part 9: Carrying on the Torch of the Market Socialists

Part 10: All Models are Wrong, Except When We Pretend They Are Right

Part 11: Building on a Broken Foundation

Part 12: Models and Theories

Part 13: No Other Game in Town

Part 14: A Pretense of Knowledge in Macroeconomics

Part 15: Where Do We Go From Here?

If you made it through all of them I’m not sure if I should congratulate you or feel sorry for you, but either way thanks for reading.

What’s Wrong With Modern Macro? Part 15 Where Do We Go From Here?

I’ve spent 14 posts telling you what’s wrong with modern macro. It’s about time for something positive. Here I hope to give a brief outline of what my ideal future of macro would look like. I will look at four current areas of research in macroeconomics outside the mainstream (some more developed than others) that I think offer a better way to do research than currently accepted methods. I will expand upon each of these in later posts.

Learning and Heterogeneous Expectations

Let’s start with the smallest deviation from current research. In Part 8 I argued that assuming rational expectations, which means that agents in the model form expectations based on a correct understanding of the environment they live in, is far too strong an assumption. To deal with that criticism, we don’t even need to leave the world of DSGE. A number of macroeconomists have explored models where agents are required to learn about how important macroeconomic variables move over time.

These kinds of models generally come in two flavors. First, the econometric learning models summarized in Evans and Honkapohja’s 2001 book, Learning and Expectations in Macroeconomics, which assume that agents in the model are no smarter than the economists that create them. They must therefore use the same econometric techniques to estimate parameters that economists do. Another approach assumes even less about the intelligence of agents by only allowing them to use simple heuristics for prediction. Based on the framework of Brock and Hommes (1997), these heuristic switching models allow agents to hold heterogeneous expectations in equilibrium, an outcome that is difficult to achieve with rational expectations, but prevalent in reality. A longer post will look at these types of models in more detail soon.


Most macroeconomic research is based on the same set of historical economic variables. There are probably more papers about the history of US macroeconomics than there are data points. Even if we include all of the countries that provide reliable economic data, that doesn’t leave us with a lot of variation to exploit. In physics or chemistry, an experiment can be run hundreds or thousands of times. In economics, we can only observe one run.

One possible solution is to design controlled experiments aimed to answer macroeconomic questions. The obvious objection to such an idea is that a lab with a few dozen people interacting can never hope to capture the complexities of a real economy. That criticism makes sense until you consider that many accepted models only have one agent. Realism has never been the strong point of macroeconomics. Experiments of course won’t be perfect, but are they worse than what we have now? John Duffy gives a nice survey of some of the recent advances in experimental macroeconomics here, which I will discuss in a future post as well.

Agent Based Models

Perhaps the most promising alternative to DSGE macro models, an agent based model (ABM) attempts to simulate an economy from the ground up inside a computer. In particular, an ABM begins with a group of agents that generally follow a set of simple rules. The computer then simulates the economy by letting these agents interact according to the provided rules. Macroeconomic results are obtained by simply adding the outcomes of individuals.

I will give examples of more ABMs in future posts, but one I really like is a 2000 paper by Peter Howitt and Robert Clower. In their paper they begin with a decentralized economy that consists of shops that only trade two commodities each. Under a wide range of assumptions, they show that in most simulations of an economy, one of the commodities will become traded at nearly every shop. In other words, one commodity become money. Even more interesting, agents in the model coordinate to exploit gains from trade without needing the assumption of a Walrasian Auctioneer to clear the market. Their simple framework has since been expanded to a full fledged model of the economy.

Empirical Macroeconomics

If you are familiar with macroeconomic research, it might seem odd that I put empirical macroeconomics as an alternative path forward. It is almost essential for every macroeconomic paper today to have some kind of empirical component. However, the kind of empirical exercises performed in most macroeconomic papers don’t seem very useful to me. They focus on estimating parameters in order to force models that look nothing like reality to nevertheless match key moments in real data. In part 10 I explained why that approach doesn’t make sense to me.

In 1991, Larry Summers wrote a paper called “The Scientific Illusion in Empirical Macroeconomics” where he distinguishes between formal econometric testing of models and more practical econometric work. He argues that economic work like Friedman and Schwartz’s A Monetary History of the United States, despite eschewing formal modeling and using a narrative approach, contributed much more to our understanding of the effects of monetary policy than any theoretical study. Again, I will save a longer discussion for a future post, but I agree that macroeconomic research should embrace practical empirical work rather than its current focus on theory.

The future of macro should be grounded in diversity. DSGE has had a good run. It has captivated a generation of economists with its simple but flexible setup and ability to provide answers to a great variety of economic questions. Perhaps it should remain a prominent pillar in the foundation of macroeconomic research. But it shouldn’t be the only pillar. Questioning the assumptions that lie at the heart of current models – rational expectations, TFP shocks, Walrasian general equilibrium – should be encouraged. Alternative modeling techniques like agent based modeling should not be pushed to the fringes, but welcomed to the forefront of the research frontier.

Macroeconomics is too important to ignore. What causes business cycles? How can we sustain strong economic growth? Why do we see periods of persistent unemployment, or high inflation? Which government or central bank policies will lead to optimal outcomes? I study macroeconomics because I want to help answer these questions. Much of modern macroeconomics seems to find its motivation instead in writing fancy mathematical models. There are other approaches – let’s set them free.

Some Thoughts on Universal Basic Income

People who oppose redistribution from the rich to the poor generally give two types of arguments against it. Perhaps the more obvious argument comes from a natural rights perspective – the person who created the wealth has a right to do whatever they want with it. However, if you don’t believe in free will (as I don’t), then this reasoning doesn’t make much sense. If you weren’t truly responsible for the circumstances that led you to create the wealth in the first place, why should you get to keep all of it? Shouldn’t some of it go to all of the people that had any influence on getting you to that position?

The stronger argument derives from incentives. Taking from the productive to give to the unproductive makes being unproductive far more attractive and we end up with a society where perfectly capable people choose not to work because they expect others to support them. Any attempt to solve poverty needs to deal with this issue, which makes designing anti-poverty measures difficult.

Our current welfare system has some checks in place that attempt to circumvent incentive problems, but it doesn’t solve them completely. Many of our current welfare programs involve cutoff levels where benefits begin to be reduced and eventually disappear altogether. This type of program introduces an implicit marginal tax on low income earners. Not only do they have to pay a higher official tax rate as their income rises, but they also lose some of the benefits they received at a lower income.

A simple way around this problem is to never phase out those benefits – to give them to everyone. This idea forms the backbone of the Universal Basic Income (UBI). One of the most complete proposals for a UBI comes from Charles Murray (yes, the same Charles Murray who gets kicked off college campuses because of his dangerous right wing ideas). In his version (laid out in his book In Our Hands), each American over the age of 21 would receive $13,000 per year in benefits unconditionally. Of this money, $3,000 has to be spent on health insurance, but the rest comes with no strings attached.

Of course, such a plan would be incredibly expensive. However, as Murray points out, our current system is already expensive. According to his calculations, if we eliminated our entire welfare system (including Social Security and Medicare), we could more than pay for the UBI. Getting rid of these programs would be difficult politically, but Murray offers several reasons why doing so would be desirable for almost everyone. Most notably, he estimates that poverty would be all but eliminated under his program vs the approximately 15% that remains under our own system.

Murray’s justification for some level of redistribution is similar to my own:

Inequality of wealth grounded in unequal abilities is different. For most of us, the luck of the draw cuts several ways: one person is not handsome, but is smart; another is not as smart, but is industrious; and still another is not as industrious, but is charming. This kind of inequality of human capital is enriching, making life more interesting for everyone. But some portion of the population gets the short end of the stick on several dimensions. As the number of dimensions grows, so does the punishment for being unlucky. When a society tries to redistribute the goods of life to compensate the most unlucky, its heart is in the right place, however badly the thing has worked out in practice
Charles Murray (2016) – In Our Hands

If we accept that some redistribution is desirable, a UBI seems like a more efficient way to carry it out than our current welfare setup. One common argument against the UBI is that it doesn’t make sense to waste resources on the rich. Bryan Caplan has given some arguments along these lines and argues that phasing benefits out gradually would avoid the implicit marginal tax rate problems without needing to give benefits to everyone. And it makes sense. If our goal is to eliminate poverty why not focus our efforts there?

But I don’t think that argument really works when you consider that a UBI is inextricably linked to the tax system. A UBI doesn’t look so universal after you consider that the rich are going to be paying for almost all of it. Everyone might get a check for $13,000, but top income earners pay far more than that in taxes. Their net benefit from government programs would still be strongly negative even after receiving the UBI. Depending on your perspective towards redistribution, this feature could actually be a negative, but given that redistribution is going to happen anyway, the UBI seems like a more efficient way of actually doing it.

It’s obviously not without fault, but I do think a UBI would be an improvement over our current system and I definitely recommend reading Murray’s book (it’s not that long) to anyone who wants to help the poor but believes we can do better than we do now.