The central question of this paper is: what has Kant’s Refutation of Idealism argument proven, if anything? What is the real scandal of philosophy and universal human reason? I argue that Kant’s Refutation argument can only be considered as sound if we assume that his target is what I call ‘metaphysical external-world skepticism’ (rather than traditional ‘epistemological external-world skepticism’). What is in question is not the ‘existence’ of outside things, but their very ‘nature’, that is, the claim that the thing outside us, which appears to us as persistent body in space, exists in itself as a substantia noumenon. Assuming the indirect-realist view that we only immediately know ideas and that their putative objects are known by inference, the metaphysical external-world skeptic doubts that the nature of things outside oneself is mind-independent.
JacobiF.H.1994. “On Transcendental Idealism.” Supplement to David Hume on Faith or Idealism and Realism a Dialogue
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