....The philosopher Daniel Dennett has offered a theory of consciousness that takes the metaphor of computer simulation further. To understand his theory we have to grasp two technical ideas from the world of computers: the idea of vitual machine, and the distinction between serial and parallel processors. I'll have to get the explanation out of the way first.
A computer is a real machine, hardware in a box. But at any particular time it is running a program that makes it look like another machine, a vitual machine. This has long been true of all computers, but modern 'use-friendly' computers bring home the point especially vividly. At the time of writing, the market leader in user-friendliness is widely agreed to be the Apple Macintosh. Its success is due to a wired-in suite of programs that make the real hardware machine - whose mechanisms are, as with any computer, forbiddingly complicated and not very compatible with human intuition - look like a different kind of machine: a virtual machine, specifically designed to mesh with the human brain and the human hand. The virtual machine known as the Macintosh User Interface is recognizably a machine. It has buttons to press, and slide controls like a hi-fi set. But it is a virtual machine. .....
I now turn to the other background idea that we need to import from computer science, the idea of serial and parallel processors. Today's digital computers are mostly serial processors. They have one central calculating mill, a single electronic bottleneck through which all data have to pass when being manipulated. They can create an illusion of doing many things simultaneously because they are so fast. A serial computer is like a chess master playing twenty opponents but actually rotating around them. Unlike the chess master, the computer rotates so swiftly and quietly around its tasks that each human user has the illusion of enjoying the computer's exclusive attention. Fundamentally, however, the computer is attending to its users serially.
Recently, as part of the quest for ever dizzying speeds of performance, engineers have made genuinely parallel processing machines. One such is the Edinburgh Supercomputer, which I was recently priviledged to visit. It consists of a parallel array of some hundreds of 'transputers', each one equivalent in power to a contemporary desk top computer. The supercomputer works by taking the problem it has been set, subdividing it into smaller tasks that can be tackled independently, and farming out the tasks to gangs of transputers. The transputers take the sub-problem away, solve it, hand in the answer and report for a new task. Meanwhile other gangs of transputers are reporting in with their solutions, so the whole supercomputer gets to the final answer orders of magnitude faster than a normal serial computer could.
I said that an ordinary serial computer can create an illusion of being a parallel processor, by rotating its 'attention' sufficently fast around a number of tasks. We could say that there is a virtual parallel processor sitting atop serial hardware. Dennett's idea is that the human brain has done exactly the reverse. The hardware of the brain is fundamentally parallel, like the Edinburgh machine and it runs sofware designed to create an illusion of serial processing: a serially processing virtual machine riding on top of parallel architecture. The salient feature of the subjective experience of thinking, Dennett thinks, is the serial 'one-thing-after-another', 'Joycean' stream of consciousness. He believes that most animals lack this serial experience, and use brains directly in their naive, parallel-processing mode. Doubtless the human brain, too, uses its parallel architecture directly for many of the routine tasks of keeping a complicated survival machine ticking over. But in addition, the human brain evolved a software virtual machine to simulate the illusion of a serial processor. The mind with its serial stream of consciousness, is a virtual machine, a 'user-friendly' way of experiencing the brain, just as 'Macintosh User 'Interface' is a user-friendly way of esperiencing the physical computer inside its grey box.
It is not obvious why we humans needed a serial virtual machine, when other species seem quite happy with their unadorned parallel machines.....
Adapted from Dawkins, R. (1989) The Selfish Gene. Oxford University Press. pp 278-280
What do you think?
Read the last line in the extract and say why you think the mind needs a serial virtual machine.
Vocabulary
attending to something = dealing with something, seeing to something
atop = on top of
bottleneck = something that constrains flow
dizzying = something that amkes your head spin, that makes you dizzy
farming out = giving work to someone else
orders of magnitude = multiples of ten
