Kant and Sidgwick on the objectivity and practical reason

This paper compares Kant’s and Sidgwick’s arguments in defense of objective practical knowledge. While Kant focuses on practical truths in terms of practical laws governing the mind in action, Sidgwick is concerned with practical truths about action. This is a crucial difference in the understanding of practical knowledge, which is matched by a different understanding of moral phenomenology and of the significance of subjective experience in accounting for the authority of moral obligations. Key to these differences is a more fundamental divergence regarding reflection and its impact on agency. On the Kantian view, reflection is inherent to rational action, understood as the result of the activity of reason. On Sidgwick’s view, instead, reflection is direct reflection on the nature of the proposition in question, that is, first-order judgment. This difference affects the prospects of their respective arguments against ethical naturalism, the view that the normative phenomena relative to right and wrong can be explained away in terms of desires and other psychological mechanisms. Ultimately, the Kantian view allows for a more promising conception of ethical objectivity.