Bryan Caplan thinks he’s debating me about mental illness. He’s not. Sometimes he posts some thoughts he has been having about mental illness, with or without a sentence saying “this is part of my debate with Scott”. Then I write a very long essay explaining why he is wrong. Then he ignores it, and has more thoughts, and again writes them up with “this is part of my debate with Scott”. I would not describe this as debating. Call it unibating, or monobating, or another word ending in -bating which is less polite but as far as I can tell equally appropriate.

Although he doesn’t answer my rebuttals, he does diligently respond to various unrelated posts of mine, explaining why they must mean I am secretly admitting he was right all along. When I wrote about the scourge of witches stealing people’s penises, Caplan spun it as me secretly admitting he was right all along about mental illness. Sometimes I feel like this has gone a bit too far - when I announced I had gotten married, Caplan spun it as me secretly admitting he was right all along about mental illness.

Let it be known to all that I am never secretly admitting Bryan Caplan is right about mental illness. There is no further need to speculate that I am doing this. If you want to know my position vis-a-vis Bryan Caplan and mental illness, you are welcome to read my four thousand word essay on the subject, Contra Contra Contra Caplan On Psych. You will notice that the title clearly telegraphs that it is about Bryan Caplan and mental illness, and that (if you count up the contras) I am against him. If that ever changes, rest assured I will telegraph it in something titled equally clearly.

Bryan’s latest volley in this shadow war is The Szaszian Fork: Another Reply To Scott Alexander On Mental Illness. In an earlier post, I had written that it was somewhere between undesirable and impossible to have an apolitical taxonomy of mental disorders. Caplan asks if this means I am secretly agreeing with his position: that all mental illness is just voluntary preferences, some of which are stigmatized for political reasons.

Left: my position. Right: my position, “rounded off” to Caplan’’s position

In particular, he claims I am FORCED to either accept that all mental illnesses are just “preferences” and so not illnesses at all, or as posited in a response by Emil Kierkegaard, that homosexuality is a mental illness and therefore bad.

You will not be surprised to learn that I don’t think of myself as secretly admitting this, or forced into doing anything.


Bryan mentions how I have already addressed his fork with a much more in-detail discussion of how we classify something as a disease or not at this link, to which I would add this post as fleshing out the same framework. Put simply, declaring something a “disease” is a complex category-boundary-drawing issue that combines facts and values, just like all category-boundary-drawing issues.

I said that it’s a political question whether or not you classify homosexuality as an illness. Caplan thinks of this as some sort of incredibly deep concession. But it’s a political question whether or not to classify any condition, including physical conditions, as illnesses. It’s just that the political question is usually very easy. This shouldn’t be surprising - most political questions are easy! “Should we set every tree in the United States on fire, then dump the entire Strategic Uranium Reserve in the Mississippi River?” - this is a political question, in the sense that you could propose it for a vote and people would have to form an opinion on it. It doesn’t show up on C-SPAN because it doesn’t satisfy anybody’s values. It’s a political fight where one side has a constituency of zero.

In the same way, “is cancer a disease?” is a political question. Maybe cancer makes you cough up blood and die. Basically everyone is against this, so it’s easy to condemn it and agree that doing it is worse than not doing it. If for some reason there were some strong political constituency in favor of coughing up blood and dying, who thought were were unfairly stigmatizing this wonderful prosocial activity, then we would have to have a political fight about it. This fight would have to involve comparing values (eg being against death) rather than comparing facts (eg cancer is caused by a mutation in such and such a gene).1

(see also: The Tails Coming Apart As Metaphor For Life and Ambijectivity. Categories often contain a simple region where they operate perfectly and where it would be perverse to consider them a political question even though they sort of are, and a more complex region where they start to break down and we have to agree on some final border)

Is Down Syndrome a disease? It often causes poor health and low IQ; I’m pretty against both of these things, so I would say yes. Still, there are a bunch of people who argue it isn’t, maybe because they don’t care what your health or IQ is, or because they think stigmatizes Down Syndrome patients. I think these people are wrong, but only in the same way that I think people who support the Russian invasion of Ukraine, or who hate free speech, are wrong: they have bad values, they’re against human flourishing, they’re on the wrong side of a political question.

Is depression an illness? It causes you to be miserable and not be able to do most of the things you want to do. Same story. I can’t imagine anyone being in favor of this, and I hope there’s a broad base of support to continue classifying it as an illness - but it’s a value judgment.

Caplan says okay, maybe sometimes in some ways the category boundary drawing is hard, but he proposes a bright-line rule:

No preference is a disease. No matter how bizarre or horrible (or common or wonderful). Diseases are constraints, not preferences.

Part of my frustration with Caplan is that I feel like I have proven this constraint/preference distinction incoherent and misleading again and again over the course of our “debate” and he’s never responded. He just keeps saying “but the constraint/preference distinction!” For the sake of completeness, I’ll give my summary of what he thinks the distinction is, plus four of what I consider to be the strongest counterarguments.

My interpretation of Bryan’s theory (I’m putting this in a quote block to specify I’m devil’s-advocating it, but this is my summary and not his):

If we think like behaviorists, all we can really see about mental illnesses are unusual behaviors. For example, a depressed person stays in bed all day and doesn’t work. An alcoholic drinks himself to death. A psychotic person runs out in the street naked claiming to be God.

These seem like choices. You can imagine the depressed person choosing to throw parties and work hard instead. You can imagine the alcoholic choosing to throw out his beer and never drinking again. You can imagine the psychotic person choosing to put on his clothes and act normally. In fact, if you put a gun to the alcoholic’s head and threatened to shoot him if he ever drank again, probably he would stop drinking. Therefore, we should model these conditions as unusual preferences/choices, not as diseases. The hallmark of a disease is a constraint, something you cannot “choose” to overcome, something you couldn’t overcome even with a gun to your head. For example, a paralyzed person cannot choose to walk no matter how hard she wants to, or how dire the consequences for not walking. Therefore, paralysis is an unusual constraint, and depression is an unusual preference.

We may choose (for political reasons) to stigmatize certain unusual preferences. Maybe the people who have them will choose (for signaling reasons) to cooperate in their own stigmatization. But realistically these are just completely voluntary preferences. If we don’t like them, we should ask the people who have them to choose differently, instead of treating them as diseased.

My counterarguments:

— 1: Counterargument From Physical Illness, Part I

The simple preference/constraint model clearly doesn’t describe mental illness very well. But it’s actually much worse than that. It doesn’t even describe physical illness.

Consider a migraine. If we think like behaviorists, all we can really say about migraines is that someone locks themselves in a dark room, clutches their head, and says “oww oww oww” a lot. If we put a gun to a migraneur’s head and threatened to kill them if they didn’t go to a loud party, they would grudgingly go to the party. So clearly (says a hypothetical version of Caplan, whose answers I must rely on because the real Caplan has never addressed this objection) migraine headaches are a preference, not a disease! Some people just like locking themselves in dark rooms, clutching their head, and saying “oww oww oww” a lot! If other people call this a “disorder”, they’re choosing to stigmatize migraineurs; if migraineurs agree it’s a disorder, they’re just trying to escape responsibility for their antisocial choices.

You could say the same about many - maybe most - physical diseases. Why not say that chronic pain is just a preference for grimacing a lot? That itchy rashes are just a preference for scratching yourself a lot? That colds are just a preference for lying in bed and blowing your nose a lot? (I believe most people with colds could get up, go to work, and avoid blowing their noses, if their lives depended on it).

Or we could stop thinking like behaviorists , a philosophy which nobody has taken seriously since the 1970s. Once we agree that people are allowed to have internal states, and that the rest of us are allowed to acknowledge those internal states, the paradox disappears. We can agree that the essence of migraine headaches is pain, especially pain in response to strong sensations. The essence of itchy rashes is a feeling of itchiness, which is relieved when we scratch it. The essence of colds is feeling unwell and ugh and wanting to stay in bed and having unpleasant congestion in your nasal passages. None of these particularly change your preferences. Both I (never had a migraine) and the average migraineur have a preference for not having our head be in terrible pain. But the migraineur needs to avoid bright lights in order to satisfy this preference, and I don’t. So she very reasonably avoids bright lights.

Once we’ve admitted this, it’s natural to also admit that depression involves negative emotions and low energy, that alcoholism involves a craving to drink alcohol, and that psychosis involves disturbed reasoning processes which make running out in the street naked claiming to be God seem like a good idea (all with other preferences intact). This is more parsimonious than Caplan’s theory, better matches the testimony of the mentally and physically ill themselves, and doesn’t require the mentally ill to be running some 4D-chess-style network of lies (such that actually the psychotic person’s reasoning is completely normal and they’ve just managed to perfectly trick everyone into thinking that it isn’t and tell a perfectly consistent story all the time and stick with their deception even when it presents an extreme threat to their life and freedom).

— 2: Counterargument From Gradients

Preferences and constraints naturally shade into each other. Let me give three examples.

Example 1: I am a mediocre runner, able to run about 5 km before getting tired and stopping. One day, at exactly the 5 km mark, a demon appears before me, and says it will kill me unless I run another 1 km. I’m pretty upset by this, but I gather all my willpower, try really hard, and manage to run another 1 km. Then the demon appears again and says haha, I was just joking last time, but now I’ll really kill you if you don’t run another 1 km. For some reason I’m gullible, I believe it, and even though I am in extreme pain I make a herculean effort and run another 1 km. Again the demon appears and makes the same threat, and this time I say sorry, I really can’t run another inch, guess I’ll die. The demon says okay, new threat, it will kill me and my entire family horribly if I don’t run another 0.1 km, but give me $1 million if I do. I call upon some kind of reserve of courage worthy of the heroes of old, put one foot in front of the other, and make it a final 0.1 km before stopping. Again, the demon says haha, fooled you, you need to run another 0.1 km. I try this, collapse, and await my impending death.

Do we argue that I had a simple preference again running 6, 7, and 7.1 km, but that my inability to run 7.2 km was a true constraint? It seems obvious that my difficulty running 7.1 km is of the same type as my difficulty running 7.2 km, and it just passed some threshold where I couldn’t do it anymore no matter how much it mattered.

Example 2: The demon puts a dimmer switch on my leg nerves. When it’s at 100%, I have totally normal movement. When it’s at 0%, I’m paralyzed from the waist down. At 25%, I can sort of kind of walk in extreme pain. The demon threatens to kill me unless I succeed, so I shamble a short distance. Then the demon turns the switch down to 24% and threatens me again; I try my best, but fail.

I think Caplan would have to say that at every level up to 25%, I simply have a preference against walking, which is fine and voluntary and my own fault and not a disease in any way. Then at 24%, it suddenly becomes a constraint inflicted on me by an outside agency and which I deserve sympathy for.

Instead, I would rather describe things that make an action difficult and unpleasant as in some sense real constraints. When the dimmer switch is at 25%, I have an external constraint making walking difficult and unpleasant, although I can overcome this and do it anyway with a strong enough incentive. When the switch is at 24%, it’s become so difficult that no incentive can make me do it. There’s no qualitative boundary, just a quantitative one.

Example 3: Try to hold your breath as long as you can (please don’t go overboard and hold it so long you pass out). If your experience is like mine, at each moment you’ll feel like - given a slight exercise of willpower - you could choose to hold your breath one more second if you so desired. But if your experience is like mine, you will also find that no amount of love or money could make you hold your breath successfully for (let’s say) three minutes.2

Is there a point where not wanting to hold your breath any longer switches from a preference to a constraint? Or have you discovered a place, in the dark moments just before suffocation, where these concepts lose all meaning?

— 3: Counterargument From Physical Illness, Part II

Caplan claims that mental illnesses involve preferences and physical illnesses involve constraints. But a second’s thought reveals this is not actually true, even if you accept the whole preference-constraint dichotomy

Consider cancer. Cancer involves some constraints; for example, it might kill you, and you cannot choose to live instead, even if someone put a gun to your head and demanded it3. But until that happens, it mostly looks like preferences. People with cancer might stay in bed, saying they feel too sick and weak to get up and do things. But if you threatened them with a gun, they could probably get up and do things. People with cancer might refuse to eat, saying they feel too nauseous and have no appetite. But if you threatened them with a gun, they could probably get down some food.

Meanwhile, plenty of mental illnesses include constraints. One of the diagnostic criteria for depression is cognitive and memory problems; people with these problems cannot choose to remember things better, even with a gun to their head. Many people with psychosis cannot speak or reason normally, even if you put a gun to their head and ask them how a healthy person would answer a question. People having panic attacks cannot choose to have a normal heartbeat, or to stop shaking or sweating. Depression and anxiety are both associated with insomnia; try to will yourself to sleep and you’ll sleep less,not more.

Both physical and mental illnesses are complex bundles of preferences and constraints, which shouldn’t be surprising given that preference vs. constraint is an oversimplified distinction that breaks down outside its legitimate domain.

— 4: Counter-Argument From The Gun-To-The-Head Test Actually Not Working

A depressed person may not be able to get out of bed or live a normal life. This might get so bad that they decide to commit suicide by shooting themselves in the head. Confronted with a choice between living a normal life, or a gunshot to the head, they have chosen the gunshot4. It appears that they have passed the gun-to-the-head test that Caplan loves so much.

I feel bad including this one, because Caplan can fairly object that this is just another preference. Maybe depressed people completely voluntarily choose to lie in bed for a few years while falsely claiming to be miserable and then shoot themselves in the head, and all of this is a perfectly free choice that they are happy with. I cannot disprove this, only point out how unparsimonious it is.

Maybe a better example is when a psychotic person attacks the cops, the cops order him to stop or else they’ll shoot him, the psychotic person continues attacking them (eg because he believes he’s invincible) and then the police go ahead and shoot him.

Again, Caplan could say that this is just a preference for attacking cops and then being killed. But in that case he should stop touting the “gun to the head test” as meaningful. Rather, he should admit that his theory is completely unfalsifiable - no matter what actions a mentally ill person does, what tests they pass or fail, he can just say they had a preference for doing whatever they did.

In fact, at this point I don’t see why he even has to acknowledge the existence of constraints at all. One might as well claim that a paralyzed person could walk if they wanted, but chooses not to.


I think Caplan is groping towards something like the following criticism:

Suppose we simplify depression to “person lies in bed and doesn’t do anything all day”. Caplan’s model treats this as “depressed person has preference to lie in bed”. My model treats this as “depressed person has an abnormal mental/emotional/motivational state that makes it difficult and unpleasant for them to not lie in bed”.

Now we consider a gay person. Caplan’s model treats this as “person has a preference to be gay”. Wouldn’t my model have to treat this as . . . person has abnormal mental/emotional/motivational state that makes it difficult and unpleasant for them to be heterosexual?

In some sense this is true. We could imagine some very religious man from the 1950s who really wants to be straight, marry a woman, and raise a family. But due to some hormonal disturbance, he feels a very strong urge to have sex with men.

How is this different from (let’s say) depression-secondary-to-hypothyroidism, where some person really wants to live a normal life, but instead, due to a hormonal disturbance, feels unable to do anything but lie in bed?

It doesn’t seem that different to me. It also doesn’t seem that different from a straight guy who wishes he were gay (maybe for LGBTQ cred, or because it would make it much easier to find partners) but feels a very strong urge to have sex with women.

So does that mean that depression is “just a preference”? I don’t think so, because none of these scenarios seem that different from the person with the migraine either! I think the preference/constraint dichotomy is a bad way to think about about this whole class of things.

I think all of the following things shade into each other:

  1. A migraine. You could think of this as a preference for sitting in a dark room and saying “ow ow ow” - or as an internal state of head pain.

  2. An itchy rash. You could think of this as a preference for scratching yourself - or as an internal state of itchiness.

  3. Depression due to hypothyroidism. You could think of this as a preference for very low activity levels - or as an internal state of very low motivation and extreme fatigue.

  4. Homosexuality. You could think of this as a preference for having same-sex coupling - or as an internal state with a strong urge to couple with people of the same sex (or a strong repulsion towards opposite-sex coupling).

  5. Heterosexuality, as above.

  6. Liking Pepsi more than Coke. You could think of this as a preference for drinking Pepsi over drinking Coke - or as an internal state marked by a strong repulsion to Coke plus a strong attraction to Pepsi.

In the first two situations, it’s much more natural to use internal-state language, and in the sixth, it’s much more natural to use preference language. The middle three aren’t obvious, which is why we’re having this debate.

The Buddhists say desire is suffering, and sometimes this is literally true. An itch is the clearest example; it’s in an almost perfect superposition between raw suffering and pure desire (to scratch yourself). Is it a preference or a constraint? It’s both - a preference to scratch one’s self, and a constraint to be forced to feel suffering if you don’t scratch yourself. While the person may choose whether or not to scratch themselves, they cannot choose whether or not to feel the suffering. Put a gun to their head and say “stop feeling suffering when you don’t scratch yourself” and they will have no choice but to die.

It’s possible, although bizarre, to think of normal preferences like the preference for Pepsi over Coke this way. You could say “this person has the constraint that they will feel suffering when they are forced to drink Coke instead of Pepsi”. It’s not very useful. But it’s possible.

Whether it’s more useful to think of any given situation as a preference or a constraint depends on things like whether you can easily satisfy the preference, whether the preference is ego-syntonic or ego-dystonic, and whether it seems normal by social standards.

Consider Prader-Willi syndrome, caused by damage to a region of chromosome 15. Symptoms tend to include short limbs, mental retardation, and extreme hunger. Here’s how the NYT describes this last problem (content warning for body horror):

One result is a heightened, permanent sensation of hunger. “They describe it as physical pain,” Jennifer Miller, an endocrinologist at the University of Florida who treats children with Prader-­Willi, told me. “They feel like they’re going to die if they don’t get food. They’re starving.” Parents must lock their pantries, refrigerators and trash cans, and their children frequently lie and steal to get something to eat. They have been known to memorize credit-card numbers and secretly phone for delivery, use a drill to remove the door from a locked refrigerator and break into a neighbor’s garage and eat, uncooked, an entire frozen pizza.

And here’s how it describes one particular patient’s last moments:

In 2004, Peter and Gayle Girard held their annual Christmas Eve party for family members at their home in Orlando, Fla. Before dinner, they set out chips, vegetables and dip, shrimp, a bowl of punch and sodas. Their 17-year-old son, Jeremy, had Prader-­Willi, and they often hosted events at their home so he could join in while they kept an eye on him — as they believed they were doing that night. But the next morning, Jeremy’s belly was distended, and he complained of pain. At the emergency room, doctors pumped his stomach, but his condition worsened. A day passed before surgeons discovered that his stomach, which had been distended long enough to lose blood flow and become septic, had ruptured. Jeremy died that night. Only afterward did the Girards learn that other family members saw him eating more than he should have but didn’t alert them.

I insist on calling Prader-Willi syndrome a disease, and a serious one, even though the extreme hunger of Prader-Willi is continuous with/shades into the normal hunger where I would like a slice of pizza.

My preference for pizza is so easily satisfied that it rarely bothers me. It’s ego syntonic - I am fine with being the sort of person who likes pizza. It’s socially normal - everyone likes pizza. It doesn’t cause much trouble - it wouldn’t improve my life much if I stopped wanting pizza. So I think of it as a preference. If it were otherwise - the extreme hunger of someone with Prader-Willi - it would be more natural to talk about it as a compulsion, a sense of extreme pain inflicted on me when I wasn’t eating enough, something ontologically similar to a stomach flu that also produces extreme pain in the abdominal region.


None of this really addresses Caplan’s most recent post, which is, I think, a much worse point.

His current post says that either you have to believe that mental illness doesn’t exist and is just voluntary preferences which are stigmatized by society, or you have to believe that homosexuality is objectively a mental illness.

Not only are each of these incoherent ideas, they’re not even the same incoherent idea! You could easily accept one of the incoherent ideas and reject the other!

Consider the following three positions:

  1. Down’s Syndrome is a terrible disease that inflicts vast suffering on its victims. Also it inflicts suffering on society by making people unproductive. We should be very angry about this, and do everything we can do make people with Down’s Syndrome normal.

  2. Down’s Syndrome is a perfectly fine neurodiverse way of being human. Probably it has some disadvantages, but it also has some advantages, for example lots of people with Down Syndrome seem happy and kind. Calling this a “disease” unfairly stigmatizes people who are different.

  3. Down Syndrome is just a voluntary preference for having eyes that are unusually far apart, congenital heart disease, and moderate intellectual disability. If they really wanted, they could stop at any time. They’re just not motivated enough!

It’s easy to believe either 1 or 2 without believing 3; there’s no reason that any political position on whether or not to call something a disease commits you to believing it to be a “preference” rather than a “constraint”.

If Caplan wants to respond to this, or to my beliefs in general, I would prefer he start with the four arguments against the constraint/preference distinction, which I think are the crux of our disagreement.

  1. Isn’t cancer obviously, nonpolitically, an illness, in the sense that it clusters with all the other things we agree are illnesses? I think there are a few answers to this. One is that I would say Down Syndrome should also be in this category, but there are some real people who claim it’s not a disease - just because I would like for something not to be a political question, doesn’t mean it isn’t! An even better example is aging - which involves just as much biological dysfunction as cancer, is even more fatal, and yet - because some people aren’t against it and think death is good in this one weird case - it’s hard to get it classified as a disease. Most sane classifiers, presented with all diseases other than cancer and asked to determine whether cancer is inside or outside of the category, would say inside - but it’s our job to enforce that in real life, and neither “sane classifier” nor “agreeing on all other diseases” are trivial.

  2. Suppose that you put a gun to my head and threatened to kill me unless I cold hold my breath for X amount of time. And suppose we somehow ran this experiment across various parallel universes and found X was two minutes. Now suppose you instead threaten to do something much worse than kill me - let’s say destroy the world. Can I hold out for 2:01? I think maybe. This kind of question seems much more interesting to me than “is it a preference which means you have infinite willpower, or a constraint which means you have zero willpower?”

  3. Or can you? There are lots of stories of some cancer patient who “holds on” until their beloved spouse can be by their bedside. Is death, like taking a breath, something you can put off voluntarily, but whose delay requires more and more willpower until everyone eventually gives in?

  4. I hate even giving Caplan enough leeway to use this example. A depressed person doesn’t have a preference for lying in bed and doing nothing, in the sense that as long as they lie in bed and do nothing they’re happy, but if they get out of bed and do something they’re sad. They are lying in bed doing nothing and also extremely miserable. There is no world-state that can make them as happy as the non-depressed person, and I resent the brief second I have to pretend otherwise in order to do thought experiments inside Caplan’s model.