The Cartesian circle.
Start with all purpose doubt
Then once show existence of soul
Stages of argument
1. soul,
2. God , then
3. come back around to external world.
Ultimately the skeptical argument's don't work.
So the point of the earlier stages was merely to achieve certainly And once we have that earlier stages are erased
We come back to the everyday world, but having now given foundations to our knowledge.
This why I urged earlier: skeptical arguments are tentative
Give the skeptic his case
still
the soul exists
and
the soul has its powers (sensing, reasoning)
We can know the nature of mind
even if what we think we perceive does not exist,
Still we can gain good knowledge of the mind