We may say, on the basis of the Groundwork, that the moral actions are always unfathomable and that the immoral actions are unfathomable just when dress the conformity to the duty, therefore when they are contrary to the duty are fathomable. But in the Critique of Pure Reason (B 579) Kant affirms that "the real morality of actions, their merit or guilt, even that of our own conduct, thus remains entirely hidden from us". Therefore do not we know how much is ascribable to the pure effect of freedom or to the simple nature. Thus, Kant looks defends two positions. One, proclaiming that immoral actions are partially unfathomable, another a total obscurity of the moral quality of the actions. I judge, however, that, at bottom, Kant can maintain, without fall in contradiction, that (a) the contrary actions to the duty signal the wickedness of a maxim and that (b) the moral merit or moral unworthy can never be observed. To first alternative is assumed by Kant to account for experience of immoral actions (cf. Religion). The second thesis looks to have an eminently speculative bottom. It aims to show that moral quality of a maxim is undecidable metaphysically.
maxim; moral action; moral evil; freedom; unfathomable