Autonomy of practical reason and its limit : Kant's theory of practical interest

The concept of interest is one of the least treated concepts in the studies of Kant’s philosophy even though he uses this concept in every field of his philosophy. But in practical reason, Kant’s philosophy faces a specific di$culty with this concept because the reason makes itself autonomic only by excluding inclinations as motives to moral activity. This paper analyses two interest concepts, both of which Kant names practical, but with di#erent meanings: one is practical interest (1) in opposition to the pathological one; the other is also practical interest (2) but now in opposition to the theoretical or speculative one. Because of their definitions, they should be two di#erent concepts, but I maintain they are connected very closely to each other, and it is in this connection where the autonomy of the practical reason should be ensured and at the same time, where it is exposed to its limit. The concept of interest has many variations in Kant’s philosophy, in each field of theoretical, or practical reason or the capacity of judgment. But his uses of this concept are not always consistent, which is why it has been treated as peripheral or one of the “side issues”. Habermas’ Erkenntnis und Interesse contributed to the focus on this concept in the ’70s, but it seems to have been forgotten in the late years. 1 Research for this paper was supported by the Grants-in-Aid for Scientific Research (KAKENHI) and a fellowship from the Japan Society for the Promotion of Science. I am grateful to the JSPS for these supports. 2 The concepts of the speculative and the practical interest already appear in the Antinomy of Pure Reason of the First Critique (B494#.). Besides for example: the architectural interest (A475 B503); the interest in the extent and the interest in the content (A654f. B682f.). See also: V, 271. Apart from the Critique of Pure Reason, all references to Kant are to Kants gesammelte Schriften, herausgegeben von Königlichen Preußischen (später Deutschen) Akademie der Wissenschaften, Berlin, 1902#. References to the Critique of Pure Reason are to the standard A and B pagination of the first and second editions. I used the following English translations of Kant’s works: Immanuel Kant’s Critique of Pure Reason. Translated by Norman Kemp Smith. London / Basingstoke: Macmillan and Co. Ltd., 1970 (Reprinted). ‘Groundwork of the Metaphysic of Morals’, in H. J. Paton, The Moral Law. Kant’s Groundwork of the Metaphysic of Morals. A New Translation with Analysis and Notes. London: Hutchinson & Co., 1964