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.
Yin and yang
The notion of a duality can be found in many areas, such as Communities of Practice, but in this context yin and yang are better viewed as parts of an oneness that is expressed in the Tao. The term "dualistic-monism" or dialectical monism has been coined in an attempt to express this fruitful paradox of simultaneous unity and duality. Yin and yang can be thought of as complementary (rather than opposing) forces that interact to form a dynamic system in which the whole is greater than the assembled parts. According to this philosophy, everything has both yin and yang aspects (for instance, shadow cannot exist without light). Either of the two major aspects may manifest more strongly in a particular object, depending on the criterion of the observation. The yin yang (i.e. taijitu symbol) shows a balance between two opposites with a portion of the opposite element in each section.