Not in our Brains: On the Complex Relationship Between Biology and Behavior

Awais Aftab’s response to my article is informative because it expresses what I suspect is a widespread but confused inclination among psychiatrists to “have their cake and eat it.” On the one hand they do not want to be branded as reductionists, so they deny they are equating mental disorder with brain disease or brain mechanisms. Yet, they want to maintain a role for physical causation in mental disorder, because without it the link between psychiatry and medicine starts to look tenuous.

Reductionism is the implication of what Aftab is saying, however. By denying any important distinction between behavior produced by a brain disease and other, non-disease driven behavior (which I refer to here as “ordinary behavior”), he reveals himself to be, fundamentally, a neurodeterminist.

Aftab emphasizes that intentional behavior and neurological processes can co-exist, but, of course, no one would argue with this. It is how they relate to each other that is at issue. I take the view espoused by philosopher Peter Hacker, following Aristotle, who emphasizes how organisms have “powers” or capacities that depend on the nature of their bodies. Human beings have particularly sophisticated “mental” capacities that enable us to respond in an intricate and flexible way to the world around us. According to this view, we have agency or individuality, which is a consequence of the particular biological makeup of the human organism (Hacker, 2010).

I am not suggesting, therefore, that self-determined (as opposed to disease-determined) behavior is immune from biological influence. What I am doing is distinguishing brain disease, which is a specific situation in which there is a direct causal link between a biological process and behavior, from ordinary behavior. Although there is a complex interaction between biology and agency, it is wrong to think of ordinary behavior being caused by a biological process in the same way. Aftab, in contrast, wants to blur this distinction, calling it a “false binary.”

I devoted a good proportion of my original article to the reasons why behavior is the central issue. I am not denying that we can and do have personal experiences that do not manifest in behavior, including ordinary sensations, thoughts and moods and less familiar ones such as hallucinations and extreme moods. These are conceptually inextricably linked to outward behavior, however, in that the constitutive criteria for the application of mental concepts are behavioral. We recognize what we call mental disorders on the basis of particular patterns of behavior, including speech and communication.

Aftab is correct that brain diseases rarely eliminate agency altogether. The man with the brain tumor I used as an example is still making decisions and undertaking complex actions, just like people with advanced dementia. The disease does not fully determine each decision they make, but it circumscribes these decisions. It causes the individual to show an uncharacteristic pattern of behavior, which is the result of the brain disease and not an expression of the individual’s agency or character.

To the extent that a behavior, or pattern of behavior, is caused by a biological mechanism, it is not intentional or meaningful. Something that is produced by a biological process cannot simultaneously be “caused by” psychological factors (incidentally reifying the “psychological” and speaking of it as a “cause” is part of the conceptual confusion, as I explained in the original article). Biological processes do not have meaning. They are “governed by predictable regularities which . . . have nothing to do with the desires and purposes of individual human beings” (Moncrieff, 2020, p. 173

Although Aftab dismisses it as “semantic,” much hinges on what is meant by “cause,” and on the nature of the relationship between ordinary behavior and biology. We are organisms with certain sorts of bodies that have physiological needs and appetites, including hunger, pain and sexual desire. These physiological states are different from meaningful states like beliefs, emotions and moods, however, although meaning may be superimposed onto physiological states, as when we love or care about the object of our sexual desire. Physiology influences our ordinary behavior in complex and varied ways.

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