Monday, December 12, 2011

The sleeping mind

What modern materialist explanations of mind get right, I suspect, is their assumption that minds are entirely material phenomena that abide all the same physical laws as any other material we observe. But what materialist explanations get wrong, I further suspect, is nearly everything else.

It's not just the details we're wrong about; the metaphors we're using for our basic understanding of the mind are misleading. To show what I'm talking about, take as an example: sleep.

Sleep is ubiquitous for all animals possessing a nervous system of sufficient complexity. Even fruit flies appear to sleep. But sleep patterns vary to extremes from one species to another. For example, humans sleep an average of eight hours per day with nearly all sleep happening in one burst. Giraffes and cows sleep only about four hours per day, and armadillos sleep about eighteen. A house cat may sleep twice as much as its human roommate without ever sleeping more than a couple hours at a time. Ostriches sleep fifteen minutes or so at a time. Some animals sleep nocturnally; some animals' diurnal phasing changes with the seasons. Some birds and many aquatic mammals sleep with half their brain still awake, though REM sleep always requires both hemispheres. Seals sleep both in the water and on land, but they attain REM sleep only on land. And so on.

Given the wide range of sleep behaviors across different species, it strikes me as more than an accident that all animals of sufficient neural complexity sleep. Rather, it seems as though sleep is a necessary condition for self-sustained neural complexity, and the wide range of sleep behaviors we observe are animals' diverse ways of coping with the necessary but strategically disadvantaged position of being unconscious on a murderous planet.

Yet, as far as I can tell, sleep figures prominently into no modern explanation of the mind. Modern materialism's guiding metaphor for the mind remains the digital computer and its mechanical manipulation of information. But digital computers don't need sleep, so as a metaphor I doubt they'll take us but partway if anywhere to figuring out what's going on in the mind. Indeed, my guess is that computers' freedom from sleep remains one of the major limitations preventing us from making machines humanly smart, though how we should make computers need sleep is anyone's guess.

I suspect a good theory of mind will make strong claims about sleep and answer many of the puzzling questions we have about it. It will explain why complex neural systems need to shut down and reboot from time to time. And it will explain dreaming.


Laura said...

3rd paragraph, 1st sentence: alls

Craig M. Brandenburg said...

Laura— Thanks for the catch.