Harriet Fagerberg: ‘Are Mental Disorders like Software Bugs?’

This post is written by Harriet Fagerberg, a PhD student at King’s College London. Find out more about Harriet here.

Find the full paper here.

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. As Jerome Wakefield puts it:

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)

According to Wakefield and others, mental disorders can be distinguished from brain disorders in the same way as software bugs can be distinguished from hardware errors in a classical computer (see also Papineau 1994; Arpaly 2005; Graham 2013; Jefferson 2020). Not every software malfunction is a hardware malfunction even if every software state is a hardware state and thus, by analogy, not every mental dysfunction is a brain dysfunction even if every mental state is a neural state.

In other words, mind-brain physicalism is not sufficient to establish that all mental disorders are brain disorders.

Nevertheless, because dysfunctions count as genuine medical disorders (per the natural dysfunction analysis of medical disorder) purely mental dysfunctions still count as real medical disorders. Accordingly, the argument from the computer analogy allows us to postulate legitimate mental disorders, without brain dysfunction, and without appealing to some spooky dualism about the mental.

The argument from the computer analogy is as such both intuitive and appealing. However, as I argue in ‘Why mental disorders are not like software bugs’, it is also unsound. The argument rests on the false premise that mind-brain is analogous to software-hardware in all relevant ways. In fact, as I show, there is an important disanalogy between mind-brain and software hardware: software functions need not be hardware functions, but mental functions are brain functions.

To see why, we must get clear on what our best philosophical theories imply for the relationship between software functions and hardware functions and, in turn, the relationship between mental functions and brain functions. The standard etiological or ‘selected effects’ 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 the following question: are all software functions selected effects of the hardware (such that all software functions would be hardware functions)? It would seem 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 (as opposed to some other kind of software). Thus, if there is an error in the software code which prohibits (say) the deletion of text, then this would be 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. As such, not all software functions are hardware functions.

Mental functions on the other hand – that is, naturally selected mental effects – are necessarily selected effects of the brain and, accordingly, brain functions. 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.

References

Papineau, David. 1994. "Mental disorder, illness and biological disfunction." Royal Institute of Philosophy Supplements 37: 73-82.

Wakefield, Jerome C. 2006. "What makes a mental disorder mental?." Philosophy, Psychiatry, & Psychology 13, no. 2: 123-131.

Arpaly, Nomy. 2005. "How it is not" just like diabetes": Mental disorders and the moral psychologist." Philosophical Issues 15: 282-98.

Graham, G. 2013. "Ordering disorder: mental disorder, brain disorder, and therapeutic intervention." In The Oxford handbook of philosophy and psychiatry, ed. K.W.M. Fulford, Martin Davies, Richard G.T. Gipps, George Graham, John Z. Sadler, Giovanni Stanghellini, and Tim Thornton, 512-30. Oxford: Oxford University Press

Jefferson, Anneli. 2020. "What does it take to be a brain disorder?." Synthese 197, no. 1: 249-62.