|OK, so the title of this page is a play on the title of Smolin's book The Trouble with Physics, despite the fact that this has nothing to do with String theory. But I thought that since I'd had two pages with titles starting with the same 23 characters, I might as well use them again|
The physicalist or materialist philosophy of mind seems to be fairly dominant at the moment - the alternatives of dualism, parallelism/epiphenomenalism or mentalism/idealism often seem to be thought of as something of a joke. But before you abandon all other possibilities you should take a look at some of the following problems with the physicalist philosophy.
The difference between fact and fiction
Suppose that a book describes a character with a pain in his finger. Suppose it describes it in great detail, in fact imagine that it gives details of all of the neural events which form it. Putting such a description in a book would take far too much paper, so imagine that it's stored in computer memory instead. We can then imagine a device to 'read through' this description, but this is still clearly a fictional pain.
Now consider a real pain in your finger. If physicalism is to be believed, then a robot could have a similar pain, even if it was just part of a simulation on a computer. Suppose now the we 'unwind the loops' of the computer program, so as to get a long string of instructions which the computer processor goes through. This is equivalent to the original program, so presumably the pain is still real, but we seem to have ended up with a system equivalent to the purely fictional pain described above
Can we build it - Yes we can!
In some of his earlier books, Daniel Dennett gave examples of how consciousness might be built into a machine. Thus a flow chart would show how a number of basic components might be put together - with a number of feedback loops - so as to create a conscious entity. The trouble with this is that there doesn't seem to be anything to stop you implementing one of these systems on a current computer, which we would then be expected to believe was conscious. But we don't - no matter how realistic a computer game, we wouldn't think of the characters as being conscious, even if we knew that their programming contained some fancy code. We might imagine that in the future conscious programs might be developed, but not now. However, this is always likely to be the case - if we can understand the workings of a program, then we don't ascribe consciousness to it. Hence it is hard to see how we would ever admit to a computer being conscious.
Dualism - are we already there
Suppose that we knew that dualism were true - that we had experimental evidence of another realm where mental events took place. I realise that dualism is unpopular, but its certainly possible to imagine that this might be true - and that we might have some way of accessing what was going on in the mental realm. Then, whilst others were trying to find physical explanations for mental events, we would be able to see the real explanation. The trouble is that when you begin to think about this possibility, it begins to seem like we're already there - you do have priviledged access to mental events, and if someone tries to explain what is happening in your brain via the physics and chemistry of neurons, you are likely to say 'well that's all very well, but the real reason was ...'
Life in a simulation
If we believe in physicalism then we have to accept that we might be living in someone else's computer simulation - we accept that a computer simulation might involve conscious beings, and it follows that such beings might be us. As it stands this doesn't seem so bad - after all many philosophies place our universe inside some larger entity. But who says that the simulation is of the whole universe, ever since the big bang, in the minutest quantum detail? You can only actually experience a limited space and time, and the detail you can experience is also limited. Just as a computer game will only reproduce a small part of its 'universe' in graphic detail at any one time, one would have to assume that the simulation we live in doesn't calculate all of what we think of as the laws of physics, only enough as is necessary to produce what we experience. The question then comes 'When did the simulation start running?' You may well think that you have memories going back for years, but those were just part of the initial data for the simulation. Perhaps it only started a few seconds ago. Even worse, perhaps it will end in a few seconds time. I don;t know about you, but I find such a view of the universe very difficult to accept.
|The worry that our universe only formed a few seconds ago comes up in other contexts as well, for instance in thoughts about thermodynamics and the arrow of time.
You might not feel that any of the above problems are serious enough to make you give up on physicalism - I'm not sure how seriously I take them myself, and I'm certainly not trying to push any of the alternative philosophies of mind - these have problems of their own. But I hope that I've shown that the physicalist philosophy of mind still has quite a few questions to answer.