We do not like to think about our brains. When we look at the world we conveniently gloss over the sensation that the living person who sees seems to be located behind our eyes, in that cranial bowl of inert, grey paste. Our niceness in this respect even shows itself in our eating. The idea of eating brains is repulsive to most, which is strange given the other glands and organs we dine off - what are kidneys used for? But eating it would confront us with the fact that the brain really is an organ, and physical. From the inside it feels neither of these things.
Unfortunately the advent of computers has given us some troublesome metaphors and analogies. In earlier days of pre-lapsarian computer innocence, we might accept the brain's workings as mysteries too deep to fathom, or even comprehend. Now, though, we are almost forced to articulate concerns which were perhaps better left unspoken.
For example, all computer users know that you can never have enough memory. When you run out - as always happens - you either upgrade your capacity, or you throw away old files to make room for new data. The brain too stores data, though how is not clear in detail. An obvious question poses itself: does the brain ever run out of memory? Or, equivalently: just how finite is the brain?
As we blithely go through life, experiencing, learning, remembering, we assume that this state of affairs will continue until we die. The idea that the brain might at some point become full, become incapable of learning or remembering any more, is terrifying. But not ridiculous: the brain evolved in hominids whose life expectancy was around 35 years, not 70, and who moreover led a relatively simple and uneventful life. Today, people probably experience more new sensations and ideas in a month than their distant forebears did in their entire lives. Has the brain enough spare capacity to cope with this excess?
If it hasn't, what will happen - given that there are, as yet, no upgrades for the brain? The best we can hope for is that the brain will dump old memories and knowledge just as we delete old files. We might lose treasured moments and hard-won skills from the past, but at least we would have room for the future. This does, in any case, clearly happen: nobody remembers all their childhood, and the older you get, the less you recall from long ago.
Worse would be the situation where we simply forget everything we see or do or learn beyond a certain time. If this were proved to happen, our whole attitude to life would alter. No longer would we thoughtlessly be hungry for new knowledge and experiences; we would need to ration them, to apportion them year by year. We would become parsimonious with our brain, costive with its valuable capacity. Of course just as some poor fools now smoke and drug themselves heedless of the eventual damage, so we would have info addicts who gorged themselves on facts today, reckless of tomorrow. For the rest of us there would be anti-education programmes, even government mental health warnings on books, art, music, on everything offering a new idea or experience. It makes you think, doesn't it?