John Stuart Mill sites the following statement from Kant as evidence of Kant’s philosophical reliance upon a similar teleological or utilitarian ethic (Mill says that even Kant had to appeal to the principle of utility): “So act that the rule on which thou actest would admit of being adopted as a law by all rational beings.” Kant’s statment does read as a universal first principle of morality’s origin and basis. I think it a mistake, however, to attribute to Kant the same ethical utility as advanced by Mill. Kant seems satisfied with universal ethical principle.
He places more emphasis, however, on one’s inclinations and the effects of these inclinations on the overall moral/ethical product than does Mill. Mill, in fact, considers inclinations and Kantian ideas of duty as irrelevant in any designation of moral/ethical values and/or consequences. The result itself is, for Mill, praiseworthy, regardless of inclinations, if it perpetuates or leads toward the summum bonum (highest good). Kant, on the other hand, would argue that a true ethic - an ethic based upon duty rather than those inclinations which lead to amoral and worthless actions - possesses the potential to lead one toward unfortunate or undesirable circumstances in life, in spite of being morally/ethically praise worthy. These unfortunate and undesirable circumstances are not compatible with Mill’s utilitarian summum bonum and prohibit Kant from entering into utilitarianism as advanced by Mill.