The Critique of Pure Reoson set out to curb the pretensions of speculative metaphysics while establishing a priori those principles which must be assumed if there is to be knowledge of an objective order. These principles enable the fundamental distinction between appearance and reality to be drawn with system and authority. The same concern for objectivity can be seen in Kant’s writings on ethics and aesthetics, both of which subjects he transformed entirely. There are two Critiques (1788 and 1790) which deal with these branches of philosophy, together with an earlier and in many ways more challenging work, the Foundations of the Metaphysics of Morals (1785). These works develop systems of value which not only purport to explore in a definitive way the entire question of the objectivity of moral and aesthetic judgement, but also to bring to completion the metaphysical speculations begun in the first Critique. Kant tries to rehabilitate, through the theory of ‘practical reason’, some crucial metaphysical dogmas which theoretical reason alone is unable to establish.