evidence

The backfire effect has been greatly exaggerated

pnrj core principles, heuristics and biases, Uncategorized , , , , , , ,

Sep 8 JDN 2458736

Do a search for “backfire effect” and you’re likely to get a large number of results, many of them from quite credible sources. The Oatmeal did an excellent comic on it. The basic notion is simple: “[…]some individuals when confronted with evidence that conflicts with their beliefs come to hold their original position even more strongly.”

The implications of this effect are terrifying: There’s no point in arguing with anyone about anything controversial, because once someone strongly holds a belief there is nothing you can do to ever change it. Beliefs are fixed and unchanging, stalwart cliffs against the petty tides of evidence and logic.

Fortunately, the backfire effect is not actually real—or if it is, it’s quite rare. Over many years those seemingly-ineffectual tides can erode those cliffs down and turn them into sandy beaches.

The most recent studies with larger samples and better statistical analysis suggest that the typical response to receiving evidence contradicting our beliefs is—lo and behold—to change our beliefs toward that evidence.

To be clear, very few people completely revise their worldview in response to a single argument. Instead, they try to make a few small changes and fit them in as best they can.

But would we really expect otherwise? Worldviews are holistic, interconnected systems. You’ve built up your worldview over many years of education, experience, and acculturation. Even when someone presents you with extremely compelling evidence that your view is wrong, you have to weigh that against everything else you have experienced prior to that point. It’s entirely reasonable—rational, even—for you to try to fit the new evidence in with a minimal overall change to your worldview. If it’s possible to make sense of the available evidence with only a small change in your beliefs, it makes perfect sense for you to do that.

What if your whole worldview is wrong? You might have based your view of the world on a religion that turns out not to be true. You might have been raised into a culture with a fundamentally incorrect concept of morality. What if you really do need a radical revision—what then?

Well, that can happen too. People change religions. They abandon their old cultures and adopt new ones. This is not a frequent occurrence, to be sure—but it does happen. It happens, I would posit, when someone has been bombarded with contrary evidence not once, not a few times, but hundreds or thousands of times, until they can no longer sustain the crumbling fortress of their beliefs against the overwhelming onslaught of argument.

I think the reason that the backfire effect feels true to us is that our life experience is largely that “argument doesn’t work”; we think back to all the times that we have tried to convince to change a belief that was important to them, and we can find so few examples of when it actually worked. But this is setting the bar much too high. You shouldn’t expect to change an entire worldview in a single conversation. Even if your worldview is correct and theirs is not, that one conversation can’t have provided sufficient evidence for them to rationally conclude that. One person could always be mistaken. One piece of evidence could always be misleading. Even a direct experience could be a delusion or a foggy memory.

You shouldn’t be trying to turn a Young-Earth Creationist into an evolutionary biologist, or a climate change denier into a Greenpeace member. You should be trying to make that Creationist question whether the Ussher chronology is really so reliable, or if perhaps the Earth might be a bit older than a 17th century theologian interpreted it to be. You should be getting the climate change denier to question whether scientists really have such a greater vested interest in this than oil company lobbyists. You can’t expect to make them tear down the entire wall—just get them to take out one brick today, and then another brick tomorrow, and perhaps another the day after that.

The proverb is of uncertain provenance, variously attributed, rarely verified, but it is still my favorite: No single raindrop feels responsible for the flood.

Do not seek to be a flood. Seek only to be a raindrop—for if we all do, the flood will happen sure enough. (There’s a version more specific to our times: So maybe we’re snowflakes. I believe there is a word for a lot of snowflakes together: Avalanche.)

And remember this also: When you argue in public (which includes social media), you aren’t just arguing for the person you’re directly engaged with; you are also arguing for everyone who is there to listen. Even if you can’t get the person you’re arguing with to concede even a single point, maybe there is someone else reading your post who now thinks a little differently because of something you said. In fact, maybe there are many people who think a little differently—the marginal impact of slacktivism can actually be staggeringly large if the audience is big enough.

This can be frustrating, thankless work, for few people will ever thank you for changing their mind, and many will condemn you even for trying. Finding out you were wrong about a deeply-held belief can be painful and humiliating, and most people will attribute that pain and humiliation to the person who called them out for being wrong—rather than placing the blame where it belongs, which is on whatever source or method made you wrong in the first place. Being wrong feels just like being right.

But this is important work, among the most important work that anyone can do. Philosophy, mathematics, science, technology—all of these things depend upon it. Changing people’s minds by evidence and rational argument is literally the foundation of civilization itself. Every real, enduring increment of progress humanity has ever made depends upon this basic process. Perhaps occasionally we have gotten lucky and made the right choice for the wrong reasons; but without the guiding light of reason, there is nothing to stop us from switching back and making the wrong choice again soon enough.

So I guess what I’m saying is: Don’t give up. Keep arguing. Keep presenting evidence. Don’t be afraid that your arguments will backfire—because in fact they probably won’t.

What good are macroeconomic models? How could they be better?

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

Dec 11, JDN 2457734

One thing that I don’t think most people know, but which immediately obvious to any student of economics at the college level or above, is that there is a veritable cornucopia of different macroeconomic models. There are growth models (the Solow model, the Harrod-Domar model, the Ramsey model), monetary policy models (IS-LM, aggregate demand-aggregate supply), trade models (the Mundell-Fleming model, the Heckscher-Ohlin model), large-scale computational models (dynamic stochastic general equilibrium, agent-based computational economics), and I could go on.

This immediately raises the question: What are all these models for? What good are they?

A cynical view might be that they aren’t useful at all, that this is all false mathematical precision which makes economics persuasive without making it accurate or useful. And with such a proliferation of models and contradictory conclusions, I can see why such a view would be tempting.

But many of these models are useful, at least in certain circumstances. They aren’t completely arbitrary. Indeed, one of the litmus tests of the last decade has been how well the models held up against the events of the Great Recession and following Second Depression. The Keynesian and cognitive/behavioral models did rather well, albeit with significant gaps and flaws. The Monetarist, Real Business Cycle, and most other neoclassical models failed miserably, as did Austrian and Marxist notions so fluid and ill-defined that I’m not sure they deserve to even be called “models”. So there is at least some empirical basis for deciding what assumptions we should be willing to use in our models. Yet even if we restrict ourselves to Keynesian and cognitive/behavioral models, there are still a great many to choose from, which often yield inconsistent results.

So let’s compare with a science that is uncontroversially successful: Physics. How do mathematical models in physics compare with mathematical models in economics?

Well, there are still a lot of models, first of all. There’s the Bohr model, the Schrodinger equation, the Dirac equation, Newtonian mechanics, Lagrangian mechanics, Bohmian mechanics, Maxwell’s equations, Faraday’s law, Coulomb’s law, the Einstein field equations, the Minkowsky metric, the Schwarzschild metric, the Rindler metric, Feynman-Wheeler theory, the Navier-Stokes equations, and so on. So a cornucopia of models is not inherently a bad thing.

Yet, there is something about physics models that makes them more reliable than economics models.

Partly it is that the systems physicists study are literally two dozen orders of magnitude or more smaller and simpler than the systems economists study. Their task is inherently easier than ours.

But it’s not just that; their models aren’t just simpler—actually they often aren’t. The Navier-Stokes equations are a lot more complicated than the Solow model. They’re also clearly a lot more accurate.

The feature that models in physics seem to have that models in economics do not is something we might call nesting, or maybe consistency. Models in physics don’t come out of nowhere; you can’t just make up your own new model based on whatever assumptions you like and then start using it—which you very much can do in economics. Models in physics are required to fit consistently with one another, and usually inside one another, in the following sense:

The Dirac equation strictly generalizes the Schrodinger equation, which strictly generalizes the Bohr model. Bohmian mechanics is consistent with quantum mechanics, which strictly generalizes Lagrangian mechanics, which generalizes Newtonian mechanics. The Einstein field equations are consistent with Maxwell’s equations and strictly generalize the Minkowsky, Schwarzschild, and Rindler metrics. Maxwell’s equations strictly generalize Faraday’s law and Coulomb’s law.
In other words, there are a small number of canonical models—the Dirac equation, Maxwell’s equations and the Einstein field equation, essentially—inside which all other models are nested. The simpler models like Coulomb’s law and Newtonian mechanics are not contradictory with these canonical models; they are contained within them, subject to certain constraints (such as macroscopic systems far below the speed of light).

This is something I wish more people understood (I blame Kuhn for confusing everyone about what paradigm shifts really entail); Einstein did not overturn Newton’s laws, he extended them to domains where they previously had failed to apply.

This is why it is sensible to say that certain theories in physics are true; they are the canonical models that underlie all known phenomena. Other models can be useful, but not because we are relativists about truth or anything like that; Newtonian physics is a very good approximation of the Einstein field equations at the scale of many phenomena we care about, and is also much more mathematically tractable. If we ever find ourselves in situations where Newton’s equations no longer apply—near a black hole, traveling near the speed of light—then we know we can fall back on the more complex canonical model; but when the simpler model works, there’s no reason not to use it.

There are still very serious gaps in the knowledge of physics; in particular, there is a fundamental gulf between quantum mechanics and the Einstein field equations that has been unresolved for decades. A solution to this “quantum gravity problem” would be essentially a guaranteed Nobel Prize. So even a canonical model can be flawed, and can be extended or improved upon; the result is then a new canonical model which we now regard as our best approximation to truth.

Yet the contrast with economics is still quite clear. We don’t have one or two or even ten canonical models to refer back to. We can’t say that the Solow model is an approximation of some greater canonical model that works for these purposes—because we don’t have that greater canonical model. We can’t say that agent-based computational economics is approximately right, because we have nothing to approximate it to.

I went into economics thinking that neoclassical economics needed a new paradigm. I have now realized something much more alarming: Neoclassical economics doesn’t really have a paradigm. Or if it does, it’s a very informal paradigm, one that is expressed by the arbitrary judgments of journal editors, not one that can be written down as a series of equations. We assume perfect rationality, except when we don’t. We assume constant returns to scale, except when that doesn’t work. We assume perfect competition, except when that doesn’t get the results we wanted. The agents in our models are infinite identical psychopaths, and they are exactly as rational as needed for the conclusion I want.

This is quite likely why there is so much disagreement within economics. When you can permute the parameters however you like with no regard to a canonical model, you can more or less draw whatever conclusion you want, especially if you aren’t tightly bound to empirical evidence. I know a great many economists who are sure that raising minimum wage results in large disemployment effects, because the models they believe in say that it must, even though the empirical evidence has been quite clear that these effects are small if they are present at all. If we had a canonical model of employment that we could calibrate to the empirical evidence, that couldn’t happen anymore; there would be a coefficient I could point to that would refute their argument. But when every new paper comes with a new model, there’s no way to do that; one set of assumptions is as good as another.

Indeed, as I mentioned in an earlier post, a remarkable number of economists seem to embrace this relativism. “There is no true model.” they say; “We do what is useful.” Recently I encountered a book by the eminent economist Deirdre McCloskey which, though I confess I haven’t read it in its entirety, appears to be trying to argue that economics is just a meaningless language game that doesn’t have or need to have any connection with actual reality. (If any of you have read it and think I’m misunderstanding it, please explain. As it is I haven’t bought it for a reason any economist should respect: I am disinclined to incentivize such writing.)

Creating such a canonical model would no doubt be extremely difficult. Indeed, it is a task that would require the combined efforts of hundreds of researchers and could take generations to achieve. The true equations that underlie the economy could be totally intractable even for our best computers. But quantum mechanics wasn’t built in a day, either. The key challenge here lies in convincing economists that this is something worth doing—that if we really want to be taken seriously as scientists we need to start acting like them. Scientists believe in truth, and they are trying to find it out. While not immune to tribalism or ideology or other human limitations, they resist them as fiercely as possible, always turning back to the evidence above all else. And in their combined strivings, they attempt to build a grand edifice, a universal theory to stand the test of time—a canonical model.