Emmanuel Levinas, one of the most important ethical theorists of the 20 th century, advocated that the prioritization of the Same in identity metaphysics is the reason why the Other is neglected in Western philosophy. He changed the point of departure of philosophy and accepted ethics rather than ontology as the primary philosophy in order to deny this negative negligence of the Other. Therefore, ethics theory that prioritizes the Other to the Same is known as “ethics of the Other” and Levinas himself is known as “the philosopher of the Other”. Based on the dissertations of Levinas, the Ethics of the Other began new discussions together with attracting an intense interest in the philosophical agendum of the era. Alain Badiou, a thinker of the same continental tradition, came up with the most severe criticism on the ethics of other. Badiou objected to the consideration of the Other as a philosophical category, and attempts of theorization of ethics through the rhetorics of mercy on the Other. Badiou regarded his own ethics of truth as the only genuine ethics and considered the ethics of the other as based upon a vulgar sociology, thus he placed the former in an opposing position to the latter. In this study, an attempt is made to assess some essential problems and concepts of Levinas’s ethics of the other and Badiou’s ethics of truth through a method of diacritical hermeneutics. Within this framework, notions of “otherness and conatus essendi” are emphasized. The main aim in analyzing the ethics of Levinas and Badiou was not to achieve a reductionist categorization, but an attempt to question the philosophical meanings of the sharp contrasts between these two philosophers who made radical moves in philosophy by disengaging from classical theories of ethics, to raise alternative ways of thinking for discussion.