• cncept of mental health
• ethics

Russell Powell and Eric Scarffe1 are pluralists about disease. They offer their thickly normative account to meet the needs of doctors, but they allow that a different concept of disease might work better for zoologists.

In this commentary, I grant that Powell and Scarffe’s thickly normative evaluation of biological dysfunction works well in many medicinal contexts. Powell and Scarffe respond effectively to eliminativists—we should retain the concept of disease. But the paper’s pluralism and focus on the specific needs of institutions should permit us to eliminate the notion of disease from domains for which the historical grounding of their selected effects account of function are contrary to therapeutic goals. One such domain is mental health. I found Powell and Scarffe’s rejection of Boorse’s dispositional account of biological function persuasive—the selected effects account of function is a superior fit for biologists’ use of the term. But the historical nature of this concept is, at best, a distraction from the task of morally evaluating the many ways in which humans today function psychologically.

Brains are not like pancreases whose functions have been consistent over many millennia. Human diets have changed markedly, but the need for the pancreas to produce insulin to enable the processing of calories has remained consistent throughout. What constitutes pancreatic dysfunction in the environment of evolutionary adaptedness (EEA) is essentially similar to what constitutes pancreatic dysfunction today. But the environments we place human brains in today differ significantly from the environments for which human brains originally evolved and that define its evolved functions.

Consider the case of homosexuality in the light of the selected effects account of biological function. Suppose we were to discover that mutations that increased the likelihood of male homosexuality occurred in ancestral populations. There they had about as significant an effect on biological fitness as mutations that increased the likelihood of asthma. From the perspective of the selected effects account of disease, this seems to offer powerful support for classifying homosexuality as a disease. Perhaps evolutionary biologists would correctly view ancestral homosexuality as such. But on Powell and Scarffe’s thickly normative view homosexuality would not be a disease. It would be a case of biological dysfunction that is not properly disvalued. This is a key difference between their thickly normative account and the thinly normative views that they reject. But we should wonder what facts about selection history really add to decisions about how today’s mental health professionals approach homosexuality. The issue of how same-sex attraction affected the biological fitness of humans in ancestral populations has no bearing on the assessment that is it conducive to flourishing today.

Consider another example of psychological functioning. Today, many people express distrust of those who differ from them in ways they care about. This can manifest in hostility towards immigrants. It is reasonable to conjecture that in the EEA this tendency promoted biological fitness. Forager bands that inhabited the EEA comprised perhaps 50–100 individuals, many of whom were related. For members of small forager groups suspicion towards strangers could well have been adaptive. In today’s multiethnic societies of strangers, we see the downsides of this way of thinking, downsides likely not apparent in the forager communities of the EEA. A negative moral evaluation of this psychological tendency in the early 21st century does not mean that we must medicate those who today display their evolved clannishness on social media. But we should certainly seek other kinds of interventions—perhaps educational—to prevent this vestige of our Pleistocene psychology from expressing itself.

Cases like these suggest that we should acknowledge that the concept of disease with its conceptual linkage to ancestral environments is not particularly useful when it comes to the assessment of psychological functioning. The inclusion of an appeal to selective history may inadvertently lend support to homophobes who are misguidedly overconfident in their moral condemnation of homosexuality. Powell and Scarffe reject this view. But there are many people who today would feel confident in their moral rejection of this potential departure proper biological functioning. When we challenge homophobes, it is better to do so without the philosophical distraction of claims about how homosexuality did or did not improve biological fitness in the EEA.

The answer is not to revert to Boorse’s ahistorical account. Rather, we should acknowledge that the needs of mental health are better served by eliminating the concept of disease altogether and focusing directly on traits that today promote human flourishing. Cases in which there is an obvious need for a disease concept are those such as multiple sclerosis. Here, diagnosis is contingent on the identification of specific lesions in the brain. Perhaps advances in brain science will connect lesions in the brain to conditions that we today diagnose symptomatically. But it is likely that many ways of functioning psychologically that we may wish to discourage will not be associated with any such lesions.