Just when philosophers of science thought they had buried Freud for the last time, he has quietly reappeared in the writings of moral philosophers. Two analytic ethicists, Samuel Scheffler and John Deigh, have independently applied Freud's theory of the superego to the problem of moral motivation. Scheffler and Deigh concur in thinking that although Freudian theory doesn't entirely solve the problem, it can nevertheless contribute to a solution.

Freud claims that the governance exercised over us by morality is a form of governance that was once exercised by our parents and that was subsequently assumed by a portion of our own personalities. This inner proxy for our parents was established, according to Freud, at the time when we were obliged to give up our oedipal attachment to them. Freud therefore declares that “Kant's Categorical Imperative is … the direct heir of the Oedipus complex.”

Scheffler and Deigh are skeptical of Freud's claim to have explained the force of Kant's imperative. In Freud's thoroughly naturalistic account, our obedience to moral requirements owes nothing to their meriting obedience; it's due entirely to incentives that appeal to our inborn drives. Freud thus explains the influence of morality in a way that tends to debunk its rational authority, whereas the Categorical Imperative is supposed to carry all the authority of practical reason.

But Scheffler and Deigh believe that moral requirements can carry rational authority, as Kant believed, while still emanating from a distinct portion of the personality, formed out of identifications with other persons in the manner described by Freud.