Completing the Cartesian Circle

     Rehearsing the entire argument

1. We began with systematic doubt
     1st Meditation

Suppose (this the strongest version of skepticism) there be an evil demon

Still, we know something
     2nd Meditation

2. The soul exists

And when we examine the ideas present in the soul, we find the idea of God.

3. From the existence of the idea of God, we may infer that God exists.

4. Our errors are caused by our moral weakness (4th Meditation).
     When we use our senses as God intended, we do not err.

5. The body exists, we know that through sensation (6th Meditation)

6. And sensation also gives us perceptual knowledge of the external world (6th Meditation).

We return thus to our starting point, but now knowing that our beliefs have foundations.

We have knowledge (justified true belief) of the external world and our body.