"I think, therefore I am." - Descartes.

Are you impressed by this deep and meaningful insight into the human condition? Descartes also wrote, in his Discourse: "... philosophy affords the means of discoursing with an appearance of truth on all matters, and commands the admiration of the more simple." Now, did Descartes come up with "I think, therefore I am." before, or after pushing his tongue firmly into his cheek?

In my first blog entry I mentioned the truth values (plural) of a sentence. What are the truth values of "I think, therefore I am."? Before even attempting to answer that question, the rational philosopher is required to explain the meaning of 'truth'.

What is truth?

The nature of truth T varies with its sufficient and necessary - sn - context. For the torturer, there exist sn amounts of pain and terror such that T. For commonal truth, there exist sn people who believe T. For the courts of law, there exist sn conformities with the laws of evidence such that T. For the scientist, there exist sn conditions of repeatable observation such that T. For the philosopher, T = N + 1.

BY T = N + 1 , I mean that a potentially infinite set of conditions can be deemed to point to T. I will jump ahead and call myself a pragmatist: I have never shot anyone, but I firmly believe that 'loaded gun against head' + 'pull trigger' >> 'death' = T. My belief comes, not from personal experience but from other minds - it is reported truth.

Categories of truth

Humans excel at category invention and labelling. I am confident that it is fundamentally hard-wired: it is the foundation of language acquisition. Categories, for me, underly the whole of maths and logic. Socrates is mortal only because we humans can create a mental category labelled 'mortal' and can cause the label 'Socrates' to be placed in that labelled category.

Unfortunately, category invention is so effortless, and so intuitive once done, that we tend to think that labelling a problem solves the problem. So, in a sinking ship, we attach the label 'hole' to the problem and return to our cigars and whiskey.

Subject to the foregoing cautionary remark, I believe that the pragmatic categories of truth T as subjectively experienced, regardless of whether the experience is of a real universe or an imagined one, are these:

a) direct experience
b) direct reasoning
c) directly reported direct experience
d) directly reported direct reasoning
e) directly reported indirect experience
f) directly reported indirect reasoning
e) indirectly reported direct experience
f) indirectly reported direct reasoning
g) indirectly reported indirect experience
h) indirectly reported indirect reasoning

These categories can readily be expanded to reveal at least 200 explications of truth, each equally valid on a pragmatic basis.

Descartes' aphorism can only be, to any of us, a truth of type f. To Descartes, it was presumably a truth of type b derived from a truth of type a. This analysis shows only this truth: we commonly accept as a historical truth of type f that: {there was a person called Rene Descartes who reported that he reasoned that he knew that he thought, and that he therefore concluded that he existed} = T

Conclusion.

The statements "I am." and "I exist." do not make use of, or create, categories. 'Be', and all of its variants, are used in human language to describe the assignment of things to categories. 'I am a man.', 'Socrates was mortal.' - these assign people to categories, and by implication assign attributes to people.

'I think, therefore my brain is working.' is an assignment operation - it expresses a truth value. 'I think, therefore I am.' is not an assignment operation, hence, the 'I am' component is inherently incapable of being assigned a truth value.

Finally, I reject any philosophical notion of the non-reality of my own existence because, to paraphrase Victor Meldrew: 'cogito ergo non credo.'