There has been a long debate between Bryan Caplan and Scott Alexander about how to understand mental illness. Caplan argue that mental illness doesn’t really exist. Very briefly, Caplan uses the distinction between budget constraints and preferences in consumer choice theory to analyze the behavior of the “mentally ill”. A key part of his view is what Caplan calls the “gun to the head test.” If you point a gun to a diabetic’s head and tell them to normalize their insulin levels (without medical intervention), they won’t be able to do anything different. But if you point a gun at someone with binge eating disorder and order them to put the donut down, they can do it. This, says Caplan, shows that the binge eater is capable of doing otherwise while the diabetic is not. Therefore, the diabetic faces a constraint and suffers from a real disease, whereas the binge eater simply has a very strong preference to eat a lot of food, and therefore compulsive overeating only satisfies a preference and is not not considered a disease or disorder.
Scott Alexander replied that consumer choice theory is inadequate for understanding or classifying mental illness for a variety of reasons. Bryan offered a refutationAlexandre came back with a replicaand now Caplan has replied Again. I recommend reading the entire exchange for complete context. Although I greatly admire these two thinkers, I think that Alexandre has the strongest arguments.
At the highest level, I think Caplan gives far too much credence to the consumer choice model he uses. Economic models are useful tools, but like all social science models, they are useful because they are simplifications. The map is not the territory, and the model is not reality. And any model of human behavior that does not perfectly and completely describe reality (that is, the totality) can end up being more confusing than enlightening when applied incorrectly.
Consider the compulsive overeater. Overeating has many potential causes, of course, but one of those causes is a leptin deficiency. Leptin is a hormone that regulates hunger and the desire to eat. In his book The hungry brainStephen Guyenet describes it thus:
While a normal child may contain around 25% fat and a typical obese child may contain 40% fat, leptin-deficient children contain up to 60% fat. Farooqi explains that the main reason leptin-deficient children develop obesity is that they have “incredible urges to eat”…leptin-deficient children are almost always hungry and they almost always want to eat, even a little time after meals. Their appetite is so exaggerated that it is almost impossible to put them on a diet: if their diet is restricted, they find a way to feed themselves, including collecting stale pieces from the trash and gnawing fish sticks straight out of them. from the freezer. It is the despair of starvation.
Yes, such a person could very well drop off the donut (or trash scraps and uncooked fish sticks) if you held a gun to their head at any given time. But then what? Their behavior still strikes me as best described as a budget constraint caused by low leptin levels, not someone simply indulging their unusual and socially frowned upon preference to eat themselves into oblivion.
Another reason I find the gun to the head test unimpressive is that it contains a hidden premise that I believe cannot be substantiated. Here is how Caplan describes this test in his latest article:
The underlying premise behind this test is the idea that any behavior someone can engage in (or refrain from) under extreme and life-threatening duress is therefore something they are capable of engaging in (or refraining from) ) at any time, throughout his life. life. But I see no reason to believe it’s true. Consider, for example, the case of mothers who lifted cars off the ground to rescue their trapped children. Suppose a week before this happened, you asked these women to lift 500 pounds in the gym and found that none of them could do it. Yet a week later, they lifted much more weight than that in order to save their child. I would say it’s just to show that what a person is capable of is different in normal circumstances and in extreme circumstances.
If I understand correctly, Caplan’s argument would involve him saying that since there was at least A “incitement in the universe” which caused them to lift such an immense weight, which shows that they must have been able lifting such an immense weight throughout, and their inability to land a 500 pound deadlift the previous week was not a real hardship, it was just them expressing their preference not to lift heavy weights. This is what a simple application of consumer choice theory would imply, but it only shows the limits of consumer choice theory. Yes, Incentives Mattered In Their Car Lifting Feat, But It Matters not imply that the inability to perform such a feat under normal circumstances is therefore “voluntary” in any significant or interesting way, nor does it imply that the true inability to lift 500 pounds the previous week was in fact only ‘a preference.
(As a side note, Alexander is also unimpressed with this test, offering to “tell (Caplan) about every mentally ill person I know who has, in fact, non-metaphorically, non-hypothetically, picked a shot. fire in their heads to keep doing the things their illness made them hard to do. Are you sure this is the easily faked hill you want to die on?” But notice the asterisk above in the description of his test by Bryan, where Caplan implies that even if someone do taking a bullet to the head for altering their behavior still wouldn’t falsify his argument, because “incentives don’t matter, do they?” not involve Involuntary, even if that leaves the possibility open. When all possible outcomes of the method chosen to test their view can still be interpreted as consistent with that view, then it’s not a very impressive test, and presents it as a kind of ace in the hole for the argument does not inspire confidence.)
People are sometimes temporarily capable of things under extreme duress that they could not achieve under normal circumstances. This is both common sense and widely known. This aspect of human behavior does not fit into the simple consumer choice model of constraints and preferences – and that’s okay! Consumer choice theory is not and should not be treated as a theory at all, meant to explain and classify all forms of human behavior. It’s just an oversimplification useful for understanding a small subset of human life.
In the closing paragraphs of Caplan’s most recent message, he cites an argument by one Emil Kierkegaard that homosexuality is best understood as a mental disorder – a position Caplan disagrees with, arguing that homosexuality is simply a preference. Caplan concludes by saying:
In response to this, I will quote Ralph Waldo Emerson‘s observation that “Senseless coherence is the hobgoblin of petty minds, adored by petty statesmen, philosophers, and theologians.” To return to my opening observation, economic models – including consumer choice theory – are not perfect descriptors of all reality. And when your model doesn’t fully capture reality, training all of your beliefs to be perfectly consistent with that model isn’t automatically a virtue. The understanding we gain of the world from any of our models will always be limited and partial. In light of this fact, being a little inconsistent will often more preservation of truth as perfect consistency. And on this subject, I find the less than perfect coherence of Scott Alexander far more truth-preserving than the total coherence of Caplan or Kierkegaard.