>the actual process itself, not any idea, but the ability to
>think, what is that?

It's a dynamic process - and a thought which is an assumption.

Btw, "the ability to think" is an idea.

and, if you are correct, what can we
>trust if we continually assume?
>
>peace

That's a different question and, unfortunately, I cannot give you a precise answer. Neither will I say "nothing" nor will I say "God"... I'll say both at the same time.