This study examines the problematic nature of the “sanctity of life” and “human rights” to construct ethics to critique of eugenics in the modern era. In recent years, eugenic thought has spread in Japanese society. Two main ideological bases on which criticism of the status quo is built are modern “human rights,” such as the “right to life,” and the “sanctity of life” rooted in the Christian tradition. However, the “sanctity of life” based on the Christian tradition has lost its reality and appeal in the post-God's death era, and more so in Japan, which does not have a Christian (or, more broadly, monotheistic) cultural background. Nevertheless, “human rights” is a modern Western concept, and an aspect in which the modern Western idea of human rights, as represented by the “right to self-determination,” has itself made the “new eugenics” possible. This study focuses on three concepts: the dignity of life, human rights, and the right to self-determination, emphasizing continuity and commonality. They presuppose a metaphysical principle as the global substratum in common. In these ideas, true life is overlooked, and it seems that true “affirmation of life” cannot be derived by relying on these ideas.