 Albert argues that despite the similarities in method between the two types of reasoning, the force of a practical conclusion depends more on a particular desire than a universal principle. Since human desires differ so greatly, moral arguments are merely general and imperfectly formulated. (Super ethica, VI, 16, p. 491). These distinctions which are derived from Aristotle’s analysis of the nature of human knowledge, do not approach the understanding of science found in the philosophy of Kant. For Kant, speculation does not, and cannot, give us knowledge of being, nor should we begin with being as the object of science, as is seen in the medieval principle of existential non-contradiction. Kant restricts speculative science to a consideration of the laws of appearance. Practical science, or practical reason, in Kant’s philosophy, however, is concerned with freedom rather the natural good or the human end. Kant’s practical reason attains the kind of rigor, based on pure a priori principles, which would be impossible in the ethics of Aristotle, Albert and Thomas who are content with a science of practical reason whose domain is contingent and changeable acts. The secure foundation which Kant sought for every moral choice would be considered beyond the scope of practical reason as formulated by the medieval commentators on Aristotle’s ethics.