Disproving solipsism What do you think Descartes’ solipsism problem was? — Mww
In Meditations, Descartes wonders if all his experiences in the world are merely dreams and illusion. He asks if the people he sees are machines pretending to be human. He does not have the experience of making everything up, so he wonders if there is an evil demon producing the show. The recognition that a producer is needed divides the solipsism into a least two beings. Descartes opts for a good God over an evil demon which leads to a cosmological proof of said being.
The above is what Kant considers "assuming merely on the basis of faith" in his Preface of the B edition. The
cogito ergo sum would seem to undermine this view with the introduction of a rational agency. I read both A and B versions of the paralogisms as a dismantling of the "ergo" part of the sentence. A slice of that pie:
From all this one sees that rational psychology has its origin in a mere misunderstanding. The unity of consciousness, which grounds the categories, is here taken for an intuition of the subject as an object, and the category of substance is applied to it. But this unity is only the unity of thinking, through which no object is given; and thus the category of substance, which always presupposes a given intuition, cannot be applied to it, and hence this subject cannot be cognized at all. — ibid. B420
(The long footnote at the end of this passage gives a detailed breakdown of his reasoning)
By these criteria, solipsism is an empty statement. The judgement of what exists is a process I am engaged within but did not design. It is here that Berkeley also loses the ground to declare what is imaginary or not. Humans are in the cognition through experience business. We are not allowed into the engineering room. That is why Kant has all of our experience as active agents relate strictly to the theater of Practical Reason.