Today's post is by Harriet Fagerberg at King’s College London & Humboldt-Universität zu Berlin on her recent paper “Why mental disorders are not like software bugs” (forthcoming, Philosophy of Science).
What, if anything, is the difference between mental disorders and brain disorders? Are mental disorders brain disorders? If not, are they disorders at all? According to one prominent view in the philosophy of psychiatry, mental dysfunction does not entail brain dysfunction just as software dysfunction does not entail hardware dysfunction in a classical computer. Wakefield writes:
It is true that every software malfunction has some hardware description; that is not at issue. Rather, the point is that a software malfunction need not be a physical hardware malfunction. Analogously, even if all mental states are physical states, it does not follow that a mental dysfunction is a physical dysfunction. (p. 129, Wakefield, 2006; see also Papineau, 1994)
Nevertheless, because dysfunctions count as medical disorders (per the natural dysfunction analysis of medical disorder) purely mental dysfunctions still count as real disorders. Thus, we get real mental disorders, without brain dysfunction, and without appealing to some spooky dualism about the mental.
The argument from the computer analogy is both intuitive and appealing. However, as I argue in ‘Why mental disorders are not like software bugs’, it is also unsound. The argument from the computer analogy rests on the false premise that mind-brain is analogous to software-hardware in all relevant ways. In fact, there is an important disanalogy between mind-brain and software hardware: software functions need not be hardware functions, but mental functions are brain functions.
The etiological theory of function, on which the natural dysfunction account rests, states that F is a function of X iff F is a selected effect of X.
We can now ask, are all software functions selected effects of the hardware? It seems not. We can imagine a scenario in which the hardware designers had no idea that the hardware they were designing would eventually come to run a word processer. Thus, if there is an error in the code which prohibits (say) the deletion of text, then this is compatible with the hardware doing everything it was designed to do. The hardware was just designed to run code – and it is doing this correctly.
Mental functions, on the contrary, are necessarily selected effects of the brain. The only way in which a mental function can be configured into the mind via evolution is by being causally efficacious in the natural selection of the implementing organ – i.e. the brain. There is not pre-neural ‘mindware’ designer through which purely mental norms of operation may arise. It follows that mental functions are brain functions. Accordingly, should one fail, that failure would constitute a brain dysfunction – whether or not we can determine this from physical facts alone.
In this sense, mental disorders really aren’t like software bugs.