Kierkegaard outlined three spheres of moral existence: the aesthetic (this was a hedonistic stage marked by a fickle search for personal pleasure), the ethical (impersonal, rule-oriented, where the attainment of long-term, or delayed-pleasure rules), and religious (a realm where faith is the basis for action and decision-making.) Ultimately, and existentially, it is not possible to produce an objective ethical doctrine.

A solitary man, Kierkegaard usually published under a pseudonym. His published works include Either/Or (1843; English translation, 1944); Philosophical Fragments (1844; English translation, 1936), and Fear and Trembling (1843; English translation, 1941).