I think, therefore I am.

[Happy Monkey]

Originally Posted by jimhelm

yes, but thought is not required for existence to be real.

No, but existence is required for thought.

So, while it is true that you must exist in order to think, the thought is not proof of existence.

Um, if you must exist in order to think, then thought IS proof of existence.

You can observe the fact that you are 'thinking'... and doing so is a thought in itself... but ....

That "thought in itself" is the one referred to by Descartes that proves existence.

"I think therefore I am" is true, but it cannot be used to derive any other truths. To use your analogy, if a book contains words then it exists, but you know absolutely nothing else about the book or the words.

(A book that doesn't contain words can also exist, but cogito, ergo sum has nothing to say on that subject.)