Kevin Lande in Aeon:
The brain is a computer’ – this claim is as central to our scientific understanding of the mind as it is baffling to anyone who hears it. We are either told that this claim is just a metaphor or that it is in fact a precise, well-understood hypothesis. But it’s neither. We have clear reasons to think that it’s literally true that the brain is a computer, yet we don’t have any clear understanding of what this means. That’s a common story in science. To get the obvious out of the way: your brain is not made up of silicon chips and transistors. It doesn’t have separable components that are analogous to your computer’s hard drive, random-access memory (RAM) and central processing unit (CPU). But none of these things are essential to something’s being a computer. In fact, we don’t know what is essential for the brain to be a computer. Still, it is almost certainly true that it is one.
I expect that most who have heard the claim ‘the brain is a computer’ assume it is a metaphor. The mind is a computer just as the world is an oyster, love is a battlefield, and this shit is bananas (which has a metaphor inside a metaphor). Typically, metaphors are literally false. The world isn’t – as a matter of hard, humourless, scientific fact – an oyster. We don’t value metaphors because they are true; we value them, roughly, because they provide very suggestive ways of looking at things. Metaphors bring certain things to your attention (bring them ‘to light’), they encourage certain associations (‘trains of thought’), and they can help coordinate and unify people (they are ‘rallying cries’). But it is nearly impossible to ever say in a complete and literally true way what it is that someone is trying to convey with a literally false metaphor. To what, exactly, is the metaphor supposed to turn our attention? What associations is the metaphor supposed to encourage? What are we all agreeing on when we all embrace a metaphor?