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.
Philosophy of religion
World Religions put forth various theories which affirm life after death and different kinds of postmortem existence. This is often tied to belief in an immortal individual soul or self (Sanskrit: atman) separate from the body which survives death, as defended by Plato, Descartes, Monotheistic religions like Christianity and many Indian philosophers. This view is also a position on the mind body problem, mainly, dualism. This view then must show not only that dualism is true and that souls exist, but also that souls survive death. As Kant famously argued, the mere existence of a soul does not prove its immortality, for one could conceive that a soul, even if it is totally simple, could still fade away or lose its intensity. H.H. Price is one modern philosopher who has speculated at length about what it would be like to be a disembodied soul after death.