  Chapter Five of Eros and Civilization entitled “Philosophical Interlude” occurs as a bit of a rupture in the text. After discussing the Freudian theory of the instincts for four chapters, Marcuse takes a break from Freud and engages philosophy instead. However, this break is consistent with the purpose of the book. One of Marcuse’s main concerns in all of his work is the rationalization of domination. This was a major theme in One-Dimensional Man. This chapter also gives us a clue as to why Freud is so important for critical theory. Freud is put in opposition to the entire western philosophical tradition. The problem with the western philosophical tradition is that it constructs a view of rationality that is in compliance with the oppressive function of rationality or the form of rationality that supports domination. For example, the Kantian notion of moral duty for the sake of duty subordinates happiness to duty. Although Kant provides good reasons for this, he does not adequately address the need for happiness. According to Kant following, the moral law makes one worthy of happiness perhaps in the afterlife, but there is no real concern for happiness in the present world. 