Refutation of Ideali Idealism (I mean material idealism) is the theory that declares the existence of objects in space outside us to be either merely doubtful and in demonstrable, or else false and impossible; the former is the problematic idealism of Descartes, who declares only one empirical as sertion (assertio), namely I am, to be indubitable; the latter is the dog matic idealism of Berkeley, who declares space, together with all the things to which it is attached as an inseparable condition, to be some thing that is impossible in itself, and who therefore also declares things in space to be merely imaginary.