[Sussex] One is _not_ odd.

[Dominic]

On Saturday, March 01, 2003 9:54 AM, Steve Dobson most elequently said:

> There is such a thing as a correct answer, and at one time Pure
Mathematicians prided themselves that there answerd had no practable
application, not that their answers were wrong.

mmmm, lets apply one of the most famous theorys regarding the answers to our
own questions... (  :P )

(Taken from a discourse on the subject from an Oxford University essay)
http://easyweb.easynet.co.uk/~ursa/philos/prel1.htm

_Descartes' theory of knowledge_

Consider Descartes sitting beside the fire in his dressing gown at 10 p.m.
on 31st March 1639. He considers the proposition: "I am sitting beside the
fire in my dressing gown." And he asks, do I know this is true? He offers a
test: if there is no practicable way to achieve greater certainty, then I
shall assume that my sense impressions are true. And that's it. (The
rationale is that God is good, so She would not allow us to get into a
situation where we cannot escape error.)

Let P be the proposition that Descartes was really sitting by the fire at 10
p.m. on 31st March 1639. And let Q be the proposition that he was really in
bed. And assume that his life's experiences fully support P. That is, he did
not subsequently wake up and find it had been a dream. Descartes claims that
it is meaningful to say that Q might be true (contrary to his experience's
support for P), and we can discover whether P or Q is true only by applying
his test.

Another possibility that Descartes considers is that there is really
_no_physical_world_at_all_. Call this proposition X. He seems to think that
X is in the same category as P and Q. Clearly it is not. For P and Q are
propositions within a discourse that presupposes a physical world. X
necessarily cannot be a proposition within that discourse. It is, rather, a
proposition in some 'meta' discourse, and is actually about the physical
discourse. It says that the physical discourse does not refer to anything.
This is certainly meaningful, and testable. The test would consist in
scrutinising how one makes use of propositions within the physical
discourse, and ascertaining whether we make any reference to a 'physical
world'. Clearly we do not. We can make reference only to our ideas.
Therefore X is quite true - in its own discourse.

OK, so where were we...

Dominic