string theory

“DSGE or GTFO”: Macroeconomics took a wrong turn somewhere

pnrj cognitive science, core principles, critique of neoclassical economics, macroeconomics, market failure, Uncategorized , , , , , , , , , , , , , , , ,

Dec 31, JDN 2458119

“The state of macro is good,” wrote Oliver Blanchard—in August 2008. This is rather like the turkey who is so pleased with how the farmer has been feeding him lately, the day before Thanksgiving.

It’s not easy to say exactly where macroeconomics went wrong, but I think Paul Romer is right when he makes the analogy between DSGE (dynamic stochastic general equilbrium) models and string theory. They are mathematically complex and difficult to understand, and people can make their careers by being the only ones who grasp them; therefore they must be right! Nevermind if they have no empirical support whatsoever.

To be fair, DSGE models are at least a little better than string theory; they can at least be fit to real-world data, which is better than string theory can say. But being fit to data and actually predicting data are fundamentally different things, and DSGE models typically forecast no better than far simpler models without their bold assumptions. You don’t need to assume all this stuff about a “representative agent” maximizing a well-defined utility function, or an Euler equation (that doesn’t even fit the data), or this ever-proliferating list of “random shocks” that end up taking up all the degrees of freedom your model was supposed to explain. Just regressing the variables on a few years of previous values of each other (a “vector autoregression” or VAR) generally gives you an equally-good forecast. The fact that these models can be made to fit the data well if you add enough degrees of freedom doesn’t actually make them good models. As Von Neumann warned us, with enough free parameters, you can fit an elephant.

But really what bothers me is not the DSGE but the GTFO (“get the [expletive] out”); it’s not that DSGE models are used, but that it’s almost impossible to get published as a macroeconomic theorist using anything else. Defenders of DSGE typically don’t even argue anymore that it is good; they argue that there are no credible alternatives. They characterize their opponents as “dilettantes” who aren’t opposing DSGE because we disagree with it; no, it must be because we don’t understand it. (Also, regarding that post, I’d just like to note that I now officially satisfy the Athreya Axiom of Absolute Arrogance: I have passed my qualifying exams in a top-50 economics PhD program. Yet my enmity toward DSGE has, if anything, only intensified.)

Of course, that argument only makes sense if you haven’t been actively suppressing all attempts to formulate an alternative, which is precisely what DSGE macroeconomists have been doing for the last two or three decades. And yet despite this suppression, there are alternatives emerging, particularly from the empirical side. There are now empirical approaches to macroeconomics that don’t use DSGE models. Regression discontinuity methods and other “natural experiment” designs—not to mention actual experiments—are quickly rising in popularity as economists realize that these methods allow us to actually empirically test our models instead of just adding more and more mathematical complexity to them.

But there still seems to be a lingering attitude that there is no other way to do macro theory. This is very frustrating for me personally, because deep down I think what I would like to do as a career is macro theory: By temperament I have always viewed the world through a very abstract, theoretical lens, and the issues I care most about—particularly inequality, development, and unemployment—are all fundamentally “macro” issues. I left physics when I realized I would be expected to do string theory. I don’t want to leave economics now that I’m expected to do DSGE. But I also definitely don’t want to do DSGE.

Fortunately with economics I have a backup plan: I can always be an “applied micreconomist” (rather the opposite of a theoretical macroeconomist I suppose), directly attached to the data in the form of empirical analyses or even direct, randomized controlled experiments. And there certainly is plenty of work to be done along the lines of Akerlof and Roth and Shiller and Kahneman and Thaler in cognitive and behavioral economics, which is also generally considered applied micro. I was never going to be an experimental physicist, but I can be an experimental economist. And I do get to use at least some theory: In particular, there’s an awful lot of game theory in experimental economics these days. Some of the most exciting stuff is actually in showing how human beings don’t behave the way classical game theory predicts (particularly in the Ultimatum Game and the Prisoner’s Dilemma), and trying to extend game theory into something that would fit our actual behavior. Cognitive science suggests that the result is going to end up looking quite different from game theory as we know it, and with my cognitive science background I may be particularly well-positioned to lead that charge.

Still, I don’t think I’ll be entirely satisfied if I can’t somehow bring my career back around to macroeconomic issues, and particularly the great elephant in the room of all economics, which is inequality. Underlying everything from Marxism to Trumpism, from the surging rents in Silicon Valley and the crushing poverty of Burkina Faso, to the Great Recession itself, is inequality. It is, in my view, the central question of economics: Who gets what, and why?

That is a fundamentally macro question, but you can’t even talk about that issue in DSGE as we know it; a “representative agent” inherently smooths over all inequality in the economy as though total GDP were all that mattered. A fundamentally new approach to macroeconomics is needed. Hopefully I can be part of that, but from my current position I don’t feel much empowered to fight this status quo. Maybe I need to spend at least a few more years doing something else, making a name for myself, and then I’ll be able to come back to this fight with a stronger position.

In the meantime, I guess there’s plenty of work to be done on cognitive biases and deviations from game theory.

How do we reach people with ridiculous beliefs?

pnrj cognitive science, core principles, ethics , , , , , , , , , , , , , ,

Oct 16, JDN 2457678

One of the most unfortunate facts in the world—indeed, perhaps the most unfortunate fact, from which most other unfortunate facts follow—is that it is quite possible for a human brain to sincerely and deeply hold a belief that is, by any objective measure, totally and utterly ridiculous.

And to be clear, I don’t just mean false; I mean ridiculous. People having false beliefs is an inherent part of being finite beings in a vast and incomprehensible universe. Monetarists are wrong, but they are not ludicrous. String theorists are wrong, but they are not absurd. Multiregionalism is wrong, but it is not nonsensical. Indeed, I, like anyone else, am probably wrong about a great many things, though of course if I knew which ones I’d change my mind. (Indeed, I admit a small but nontrivial probability of being wrong about the three things I just listed.)

I mean ridiculous beliefs. I mean that any rational, objective assessment of the probability of that belief being true would be vanishingly small, 1 in 1 million at best. I’m talking about totally nonsensical beliefs, beliefs that go against overwhelming evidence; some of them are outright incoherent. Yet millions of people go on believing them.

For example, over 40% of Americans believe that human beings were created by God in their present form less than 10,000 years ago, and typically offer no evidence for this besides “The Bible says so.” (Strictly speaking, even that isn’t true—standard interpretations of the Bible say so. The Bible itself contains no clearly stated date for creation.) This despite the absolutely overwhelming body of evidence supporting the theory of evolution by Darwinian natural selection.

Over a third of Americans don’t believe in global warming, which is not only a complete consensus among all credible climate scientists based on overwhelming evidence, but one of the central threats facing human civilization over the 21st century. On a global scale this is rather like standing on a train track and saying you don’t believe in trains. (Or like the time my mother once told me about where an alert went out to her office that there was a sniper in the area, indiscriminately shooting at civilians, and one of her co-workers refused to join the security protocol and declared smugly, “I don’t believe in snipers.” Fortunately, he was unharmed in the incident. This time.)

1/4 of Americans believe in astrology, and 1/4 Americans believe that aliens have visited the Earth. (Not sure if it’s the same 1/4. Probably considerable but not total overlap.) The existence of extraterrestrial civilizations somewhere in this mind-bogglingly (perhaps infinitely) vast universe has probability 1. But visiting us is quite another matter, and there is absolutely no credible evidence of it. As for astrology? I shouldn’t have to explain why the position of Jupiter, much less Sirius, on your birthday is not a major influence on your behavior or life outcomes. Your obstetrician exerted more gravitational force on you than Jupiter did at the moment you were born.

The majority of Americans believe in telepathy or extrasensory perception. I confess that I actually did when I was very young, though I think I disabused myself of this around the time I stopped believing in Santa Claus.

I love the term “extrasensory perception” because it is such an oxymoron; if you’re perceiving, it is via senses. “Sixth sense” is better, except that we actually already have at least nine senses: The ones you probably know, vision (sight), audition (hearing), olfaction (smell), gustation (taste), and tactition (touch)—and the ones you may not know, thermoception (heat), proprioception (body position), vestibulation (balance), and nociception (pain). These can probably be subdivided further—vision and spatial reasoning are dissociated in blind people, heat and cold are separate nerve pathways, pain and itching are distinct systems, and there are a variety of different sensors used for proprioception. So we really could have as many as twenty senses, depending on how you’re counting.

What about telepathy? Well, that is not actually impossible in principle; it’s just that there’s no evidence that humans actually do it. Smartphones do it almost literally constantly, transmitting data via high-frequency radio waves back and forth to one another. We could have evolved some sort of radio transceiver organ (perhaps an offshoot of an electric defense organ such as that of electric eels), but as it turns out we didn’t. Actually in some sense—which some might say is trivial, but I think it’s actually quite deep—we do have telepathy; it’s just that we transmit our thoughts not via radio waves or anything more exotic, but via sound waves (speech) and marks on paper (writing) and electronic images (what you’re reading right now). Human beings really do transmit our thoughts to one another, and this truly is a marvelous thing we should not simply take for granted (it is one of our most impressive feats of Mundane Magic); but somehow I don’t think that’s what people mean when they say they believe in psychic telepathy.

And lest you think this is a uniquely American phenomenon: The particular beliefs vary from place to place, but bizarre beliefs abound worldwide, from conspiracy theories in the UK to 9/11 “truthers” in Canada to HIV denialism in South Africa (fortunately on the wane). The American examples are more familiar to me and most of my readers are Americans, but wherever you are reading from, there are probably ridiculous beliefs common there.

I could go on, listing more objectively ridiculous beliefs that are surprisingly common; but the more I do that, the more I risk alienating you, in case you should happen to believe one of them. When you add up the dizzying array of ridiculous beliefs one could hold, odds are that most people you’d ever meet will have at least one of them. (“Not me!” you’re thinking; and perhaps you’re right. Then again, I’m pretty sure that the 4% or so of people who believe in the Reptilians think the same thing.)

Which brings me to my real focus: How do we reach these people?

One possible approach would be to just ignore them, leave them alone, or go about our business with them as though they did not have ridiculous beliefs. This is in fact the right thing to do under most circumstances, I think; when a stranger on the bus starts blathering about how the lizard people are going to soon reveal themselves and establish the new world order, I don’t think it’s really your responsibility to persuade that person to realign their beliefs with reality. Nodding along quietly would be acceptable, and it would be above and beyond the call of duty to simply say, “Um, no… I’m fairly sure that isn’t true.”

But this cannot always be the answer, if for no other reason than the fact that we live in a democracy, and people with ridiculous beliefs frequently vote according to them. Then people with ridiculous beliefs can take office, and make laws that affect our lives. Actually this would be true even if we had some other system of government; there’s nothing in particular to stop monarchs, hereditary senates, or dictators from believing ridiculous things. If anything, the opposite; dictators are known for their eccentricity precisely because there are no checks on their behavior.

At some point, we’re going to need to confront the fact that over half of the Republicans in the US Congress do not believe in climate change, and are making policy accordingly, rolling drunk on petroleum and treating the hangover with the hair of the dog.

We’re going to have to confront the fact that school boards in Southern states, particularly Texas, continually vote to censor biology textbooks of their dreaded Darwinian evolution.

So we really do need to find a way to talk to people who have ridiculous beliefs, and engage with them, understand why they think the way they do, and then—hopefully at least—tilt them a little bit back toward rational reality. You will not be able to change their mind completely right away, but if each of us can at least chip away at their edifice of absurdity, then all together perhaps we can eventually bring them to enlightenment.

Of course, a good start is probably not to say you think that their beliefs are ridiculous, because people get very defensive when you do that, even—perhaps especially—when it’s true. People invest their identity in beliefs, and decide what beliefs to profess based on the group identities they value most.

This is the link that we must somehow break. We must show people that they are not defined by their beliefs, that it is okay to change your mind. We must be patient and compassionate—sometimes heroically so, as people spout offensive nonsense in our faces, sometimes offensive nonsense that directly attacks us personally. (“Atheists deserve Hell”, taken literally, would constitute something like a death threat except infinitely worse. While to them it very likely is just reciting a slogan, to the atheist listening it says that you believe that they are so evil, so horrible that they deserve eternal torture for believing what they do. And you get mad when we say your beliefs are ridiculous?)

We must also remind people that even very smart people can believe very dumb things—indeed, I’d venture a guess that most dumb things are in fact believed by smart people. Even the most intelligent human beings can only glimpse a tiny fraction of the universe, and all human brains are subject to the same fundamental limitations, the same core heuristics and biases. Make it clear that you’re saying you think their beliefs are false, not that they are stupid or crazy. And indeed, make it clear to yourself that this is indeed what you believe, because it ought to be. It can be tempting to think that only an idiot would believe something so ridiculous—and you are safe, for you are no idiot!—but the truth is far more humbling: Human brains are subject to many flaws, and guarding the fortress of the mind against error and deceit is a 24-7 occupation. Indeed, I hope that you will ask yourself: “What beliefs do I hold that other people might find ridiculous? Are they, in fact, ridiculous?”

Even then, it won’t be easy. Most people are strongly resistant to any change in belief, however small, and it is in the nature of ridiculous beliefs that they require radical changes in order to restore correspondence with reality. So we must try in smaller steps.

Maybe don’t try to convince them that 9/11 was actually the work of Osama bin Laden; start by pointing out that yes, steel does bend much more easily at the temperature at which jet fuel burns. Maybe don’t try to persuade them that astrology is meaningless; start by pointing out the ways that their horoscope doesn’t actually seem to fit them, or could be made to fit anybody. Maybe don’t try to get across the real urgency of climate change just yet, and instead point out that the “study” they read showing it was a hoax was clearly funded by oil companies, who would perhaps have a vested interest here. And as for ESP? I think it’s a good start just to point out that we have more than five senses already, and there are many wonders of the human brain that actual scientists know about well worth exploring—so who needs to speculate about things that have no scientific evidence?

Schools of Thought

pnrj core principles, critique of neoclassical economics , , , , , , , , ,

If you’re at all familiar with the schools of thought in economics, you may wonder where I stand. Am I a Keynesian? Or perhaps a post-Keynesian? A New Keynesian? A neo-Keynesian (not to be confused)? A neo-paleo-Keynesian? Or am I a Monetarist? Or a Modern Monetary Theorist? Or perhaps something more heterodox, like an Austrian or a Sraffian or a Marxist?

No, I am none of those things. I guess if you insist on labeling, you could call me a “cognitivist”; and in terms of policy I tend to agree with the Keynesians, but I also like the Modern Monetary Theorists.

But really I think this sort of labeling of ‘schools of thought’ is exactly the problem. There shouldn’t be schools of thought; the universe only works one way. When you don’t know the answer, you should have the courage to admit you don’t know. And once we actually have enough evidence to know something, people need to stop disagreeing about it. If you continue to disagree with what the evidence has shown, you’re not a ‘school of thought’; you’re just wrong.

The whole notion of ‘schools of thought’ smacks of cultural relativism; asking what the ‘Keynesian’ answer to a question is (and if you take enough economics classes I guarantee you will be asked exactly that) is rather like asking what religious beliefs prevail in a particular part of the world. It might be worth asking for some historical reason, but it’s not a question about economics; it’s a question about economic beliefs. This is the difference between asking how people believe the universe was created, and actually being a cosmologist. True, schools of thought aren’t as geographically localized as religions; but they do say the words ‘saltwater’ and ‘freshwater’ for a reason. I’m not all that interested in the Shinto myths versus the Hindu myths; I want to be a cosmologist.

At best, schools of thought are a sign of a field that hasn’t fully matured. Perhaps there were Newtonians and Einsteinians in 1910; but by 1930 there were just Einsteinians and bad physicists. Are there ‘schools of thought’ in physics today? Well, there are string theorists. But string theory hasn’t been a glorious success of physics advancement; on the contrary, it’s been a dead end from which the field has somehow failed to extricate itself for almost 50 years.

So where does that put us in economics? Well, some of the schools of thought are clearly dead ends, every bit as unfounded as string theory but far worse because they have direct influences on policy. String theory hasn’t ever killed anyone; bad economics definitely has. (How, you ask? Exposure to hazardous chemicals that were deregulated; poverty and starvation due to cuts to social welfare programs; and of course the Second Depression. I could go on.)

The worst offender is surely Austrian economics and its crazy cousin Randian libertarianism. Ayn Rand literally ruled a cult; Friedrich Hayek never took it quite that far, but there is certainly something cultish about Austrian economists. They insist that economics must be derived a priori, without recourse to empirical evidence (or at least that’s what they say when you point out that all the empirical evidence is against them). They are fond of ridiculous hyperbole about an inevitable slippery slope between raising taxes on capital gains and turning into Stalin’s Soviet Union, as well as rhetorical questions I find myself answering opposite to how they want (like “For are taxes not simply another form of robbery?” and “Once we allow the government to regulate what man can do, will they not continue until they control all aspects of our lives?”). They even co-opt and distort cognitivist concepts like herd instinct and asymmetric information; somehow Austrians think that asymmetric information is an argument for why markets are more efficient than government, even though Akerlof’s point was that asymmetric information is why we need regulations.

Marxists are on the opposite end of the political spectrum, but their ideas are equally nonsensical. (Marx himself was a bit more reasonable, but even he recognized they were going too far: “All I know is that I am not a Marxist.”) They have this whole “labor theory of value” thing where the value of something is the amount of work you have to put into it. This would mean that labor-saving innovations are pointless, because they devalue everything; it would also mean that putting an awful lot of work into something useless would nevertheless somehow make it enormously valuable. Really, it would never be worth doing much of anything, because the value you get out of something is exactly equal to the work you put in. Marxists also tend to think that what the world needs is a violent revolution to overthrow the bondage of capitalism; this is an absolutely terrible idea. During the transition it would be one of the bloodiest conflicts in history; afterward you’d probably get something like the Soviet Union or modern-day Venezuela. Even if you did somehow establish your glorious Communist utopia, you’d have destroyed so much productive capacity in the process that you’d make everyone poor. Socialist reforms make sense—and have worked well in Europe, particularly Scandinavia. But socialist revolution is a a good way to get millions of innocent people killed.

Sraffians are also quite silly; they have this bizarre notion that capital must be valued as “dated labor”, basically a formalized Marxism. I’ll admit, it’s weird how neoclassicists try to value labor as “human capital”; frankly it’s a bit disturbing how it echoes slavery. (And if you think slavery is dead, think again; it’s dead in the First World, but very much alive elsewhere.) But the solution to that problem is not to pretend that capital is a form of labor; it’s to recognize that capital and labor are different. Capital can be owned, sold, and redistributed; labor cannot. Labor is done by human beings, who have intrinsic value and rights; capital is made of inanimate matter, which does not. (This is what makes Citizens United so outrageous; “corporations are people” and “money is speech” are such fundamental distortions of democratic principles that they are literally Orwellian. We’re not that far from “freedom is slavery” and “war is peace”.)

Neoclassical economists do better, at least. They do respond to empirical data, albeit slowly. Their models are mathematically consistent. They rarely take account of human irrationality or asymmetric information, but when they do they rightfully recognize them as obstacles to efficient markets. But they still model people as infinite identical psychopaths, and they still divide themselves into schools of thought. Keynesians and Monetarists are particularly prominent, and Modern Monetary Theorists seem to be the next rising star. Each of these schools gets some things right and other things wrong, and that’s exactly why we shouldn’t make ourselves beholden to a particular tribe.

Monetarists follow Friedman, who said, “inflation is always and everywhere a monetary phenomenon.” This is wrong. You can definitely cause inflation without expanding your money supply; just ramp up government spending as in World War 2 or suffer a supply shock like we did when OPEC cut the oil supply. (In both cases, the US money supply was still tied to gold by the Bretton Woods system.) But they are right about one thing: To really have hyperinflation ala Weimar or Zimbabwe, you probably have to be printing money. If that were all there is to Monetarism, I can invert another Friedmanism: We’re all Monetarists now.

Keynesians are basically right about most things; in particular, they are the only branch of neoclassicists who understand recessions and know how to deal with them. The world’s most famous Keynesian is probably Krugman, who has the best track record of economic predictions in the popular media today. Keynesians much better appreciate the fact that humans are irrational; in fact, cognitivism can be partly traced to Keynes, who spoke often of the “animal spirits” that drive human behavior (Akerlof’s most recent book is called Animal Spirits). But even Keynesians have their sacred cows, like the Phillips Curve, the alleged inverse correlation between inflation and unemployment. This is fairly empirically accurate if you look just at First World economies after World War 2 and exclude major recessions. But Keynes himself said, “Economists set themselves too easy, too useless a task if in tempestuous seasons they can only tell us that when the storm is long past the ocean is flat again.” The Phillips Curve “shifts” sometimes, and it’s not always clear why—and empirically it’s not easy to tell the difference between a curve that shifts a lot and a relationship that just isn’t there. There is very little evidence for a “natural rate of unemployment”. Worst of all, it’s pretty clear that the original policy implications of the Phillips Curve are all wrong; you can’t get rid of unemployment just by ramping up inflation, and that way really does lie Zimbabwe.

Finally, Modern Monetary Theorists understand money better than everyone else. They recognize that a sovereign government doesn’t have to get its money “from somewhere”; it can create however much money it needs. The whole narrative that the US is “out of money” isn’t just wrong, it’s incoherent; if there is one entity in the world that can never be out of money, it’s the US government, who print the world’s reserve currency. The panicked fears of quantitative easing causing hyperinflation aren’t quite as crazy; if the economy were at full capacity, printing $4 trillion over 5 years (yes, we did that) would absolutely cause some inflation. Since that’s only about 6% of US GDP, we might be back to 8% or even 10% inflation like the 1970s, but we certainly would not be in Zimbabwe. Moreover, we aren’t at full capacity; we needed to expand the money supply that much just to maintain prices where they are. The Second Depression is the Red Queen: It took all the running we could do to stay in one place. Modern Monetary Theorists also have some very good ideas about taxation; they point out that since the government only takes out the same thing it puts in—its own currency—it doesn’t make sense to say they are “taking” something (let alone “confiscating” it as Austrians would have you believe). Instead, it’s more like they are pumping it, taking money in and forcing it back out continuously. And just as pumping doesn’t take away water but rather makes it flow, taxation and spending doesn’t remove money from the economy but rather maintains its circulation. Now that I’ve said what they get right, what do they get wrong? Basically they focus too much on money, ignoring the real economy. They like to use double-entry accounting models, perfectly sensible for money, but absolutely nonsensical for real value. The whole point of an economy is that you can get more value out than you put in. From the Homo erectus who pulls apples from the trees to the software developer who buys a mansion, the reason they do it is that the value they get out (the gatherer gets to eat, the programmer gets to live in a mansion) is higher than the value they put in (the effort to climb the tree, the skill to write the code). If, as Modern Monetary Theorists are wont to do, you calculated a value for the human capital of the gatherer and the programmer equal to the value of the goods they purchase, you’d be missing the entire point.