According to a well-established reading, Husserl’s notion of "material a priori" provides a radical alternative to the Kantian problematic of the deduction. Nevertheless it has been claimed by Natorp and Schlick that also the phenomenological a priori could raise a question of legitimacy and demand something as a transcendental deduction. This paper aims to explore the plausibility of such objections. The basic assumption here is that Kant’s demand for a deduction does not result from a merely subjective character of his a priori but rather from the difficult connection between the ideal validity of the rules and their concrete function within experience. The phenomenological notion of Wesenschau radicalizes such correlation and enhances its problematic implications.
Keywords: Husserl, Kant, Material a priori, Transcendental deduction, Validity.