It was in Hobbes’s writing that we properly came to the idea of a theory of rational egoism. The theory states that in using their faculty of reason to deduce what is in their own interest, human beings would ‘realise that cooperation would maximise their self-interest’ (6). Post-Hobbes, several theories of morality emerged; the theory of moral sense, in which human beings are naturally drawn to good actions and repulsed by bad ones, and the theory of perfectionism, which states that human beings should seek to maximise their potentialiaties for perfection in order to reflect the perfection of God in their own nature. These theories fail on Kant’s reading, however, because they leave moral principles up to the ‘particular arrangement of human nature or to contingent circumstances’ (G, 4:442); in other words, these theories are unable to advance principles that are timeless and universal.
Kant further criticises theological ethics as ‘intellectually dishonest…and mean’, dishonest because it ‘presupposes that we know what is right and wrong antecedently to forming our conception of God’s will’, and mean ‘because it portrays us as motivated merely by the self-interested motives of love or reward or fear of punishment rather than by any genuine concerns for other human beings’ (8). We can thus see two themes emerging that will be important for Kant’s task in the Groundwork. First, principles of morality must be universal, and therefore a priori (since they apply to human beings irrespective of time and place). Second, genuine moral motivation must be in some way ‘nobler’ than the pursuit of one’s own happiness (i.e. more than motivated by fear of punishment, for instance). Nonetheless, ‘a moral theory that has nothing to say about happiness at all would be unrealistic, for human beings do naturally desire happiness and there is no reason for moral philosophy to neglect this fact altogether’ (8-9). Kant’s task is therefore to find a genuinely universal principle of morality and a genuinely noble motivation to be moral, which allow for a proper concern with the pursuit of happiness within the framework of morality.
(Quotes are from Paul Guyer, Kant’s Groundwork for the Metaphysics of Morals)