How is it possible to arrive at valid conclusions about a mind-independent world through reflection on the necessary conditions of experience and intentionality? The present study develops this problem of objective validity with recourse to the contemporary debate on transcendental arguments. It thereby develops an argument-based approach to two paradigmatic texts of post-Kantian idealism: Hegel’s Phenomenology of Spirit and Fichte’s Science of Knowledge 1804-II. It is shown that Hegel and Fichte try to dissolve the problem of objective validity by using a method of philosophical therapy which takes on the form of an ascent to absolute knowing. The study presents a novel interpretation of Hegel’s Phenomenology, which shows it to have methodological affinities with the paradigm of geometrical construction, and of Fichte’s late Science of Knowledge, which reappraises the role of the conceptual for Fichte. Systematically, a skeptical revenge problem is developed: idealism as such is shown to be fraught with an internal tension between claims to objectivity and skepticism. It is this inner tension that motivates the reflective ascent of the transcendental approach.