Abstract
This paper concerns the role of the transcendental distinction between agents qua phenomena and qua noumena in Kant's theory of free will. It argues (1) that Kant's incompatibilism can be accommodated if one accepts the "ontological" interpretation of this distinction (i.e. the view that agents qua noumena are ontologically prior to agents qua phenomena), and (2) that Kant's incompatibilism cannot be accommodated by the "two-aspect" interpretation, whose defining feature is the rejection of the ontological priority of agents qua noumena.
The ontological interpretation allows Kant to be an incompatibilist because the ontological priority of agents qua noumena "ontologically undermines" the significance of phenomenal determinism for agents' free will. That is, since agents qua noumena are ontologically prior to agents qua phenomena, the fact that agents qua noumena are not subject to determinism is more fundamental than the fact that agents qua phenomena are subject to determinism, and it is the more fundamental fact that we should be concerned with in the metaphysical foundations of moral responsibility. Recent (independent) work by myself, Eric Watkins, and Robert Hanna is drawn on to demonstrate that the ontological interpretation can mount a better defense against some traditional objections than has often been thought.
According to the two-aspect interpretation, the transcendental distinction between agents qua noumena and qua phenomena is a semantic and epistemological distinction. Since it rejects the ontological priority of noumena, it has no way to assert that the non-determinism of agents qua noumena is more metaphysically fundamental than the determinism of agents qua phenomena. For the two-aspect interpretation, the truth of determinism must remain just as fundamental as the truth of any other characterization of agents. This means that, on the two-aspect interpretation, there is no better reason to call Kant an incompatibilist than there is to call him a compatibilist. Since Henry Allison has presented the most detailed two-aspect interpretation of the agential transcendental distinction, the arguments against the two-aspect distinction address his interpretation. Part of Allison's strategy is to argue that phenomenal determinism poses less of a problem for free will if we accept his accounts of the Second Analogy and empirical psychology. I point our problems in these accounts and argue that this strategy cannot be accepted.