Mind–body dualism
Ontological dualism makes dual commitments about the nature of existence as it relates to mind and matter, and can be divided into three different types:Substance dualism is a type of dualism most famously defended by René Descartes, which states that there are two kinds of foundation: mental and body. This philosophy states that the mental can exist outside of the body, and the body cannot think. Substance dualism is important historically for having given rise to much thought regarding the famous mind–body problem. Substance dualism is a philosophical position compatible with most theologies which claim that immortal souls occupy an independent realm of existence distinct from that of the physical world.
Atheistic existentialism
Albert Camus writes of dualisms—between happiness and sadness—as well as life and death. In "The Myth of Sisyphus", such dualism becomes paradoxical because humans greatly value their existence while at the same time being aware of their mortality. Camus believes it is human nature to have difficulty reconciling these paradoxes; and indeed, he believed humankind must accept what he called "the Absurd". On the other hand, Camus is not strictly an existential atheist because the acceptance of "the Absurd" implies neither the existence of God nor the nonexistence of God (compare agnosticism).