16 January 1998
Thank you for your comments on unit 10 of The Possible World Machine, which I received on 10 January, and your letter of 13 January. Let me deal with the letter first!
Now I see what you mean by 'a form of dualism'. The dualism in question is nothing like mind-body dualism, but rather a dualism that occurs not infrequently in metaphysics: the dualism of appearance and reality. Another example is the claim that time is unreal (there is a famous argument for the unreality of time by the 30's metaphysician McTaggart in his treatise The Nature of Existence). Or, more radical still, is Bradley's argument, in Appearance and Reality, that in reality there are no 'things' in 'relations', and therefore no space and no time. There are general problems raised by this kind of 'double think'. As the Oxford 'ordinary language' philosopher J.L. Austin once wryly commented, 'First there is the bit where you say it; then the bit where you take it back' (i.e. 'Time is unreal', 'Time is real so far as appearances go'). Arguably, the denial of free will is another example of this.
I should say, just for the record, that my sympathies lie closer to Bradley than to Austin.
To say that fatalism 'rests on a point of logic' is not to defend the fatalist position. The question now is whether the point of logic is soundly argued or not. I have my doubts. The point, according to the defender of fatalism, is simply that truth, as such, is timeless. 'It is raining in Sheffield' may be true on one occasion, false on another. But that is only because we have left the reference to time open. 'It is raining in Sheffield at 8.45 am on 16 June 1998' is a proposition which is either true or false, argues the fatalist. Either way, its truth value is fixed for all time. The same must apply, by parity of reasoning, to propositions describing human actions.
'Fixed' can be just a synonym for 'determined'. So far I would agree with you. As a matter of correct philosophical terminology, however, determinism is a thesis about efficient causation. Logically, therefore, it is possible to be a fatalist and to deny the thesis of determinism.
Now to your notes on unit 10.
1. I shall consider your remarks as an argument against scepticism. Even if our senses are deceived, our minds are clever and resourceful enough to spot the deception. Now, there is a sense in which this is clearly true. We do succeed in identifying cases of hallucination, illusion, deception. However (as Descartes famously argued in his First Meditation) this process relies on the fact that our senses are generally reliable. — GCHQ receives a mass of data, and although an enemy power could succeed in falsifying a significant portion of that data, it would be beyond the bounds of physical possibility to falsify it all: the air waves are free.
The sceptical argument, however, takes things a stage further. What is or is not 'physically' or 'practically' possible is itself based on what we have learned about the world using our senses. A brain in a vat, however intact its reasoning powers, would come to totally false conclusions if all it received was false 'data'. I cannot prove, says the sceptic, that I am not a brain in a vat.
2. Your 'marshmallow-like' object would have to have characteristics which explained how it appeared to you as a chair and to me as an African elephant. Indeed, just as we talk of the existence or non-existence of an object, we could just as well talk of the existence or non-existence of features of that object: the elephant's ears and tusks, the chair's carved wooden legs. How do we explain to one another the action of 'sitting on'/'mounting' the chair-elephant?
Interestingly, some features appear to remain invariant when we question the 'object' of our common perceptions in this way: e.g. the doubt whether, in the privacy of our respective consciousnesses, you and I see the colour we call 'red' in the same way. But that is another story!
So far as the sceptic is concerned, of course, your perceptions, or rather the perceptions that you report to me, are just further data, on a par with the data I receive from my senses. There is no neutral vantage point or impartial referee to oversee our 'agreement'.
The main point I wanted to make in this unit, however, was that we should not allow ourselves to be forced by the possibility of scepticism to the conclusion that we do not, in fact, 'see things as they are'. This is a point about the concept of perception rather than the concept of knowledge.