Process philosophy is a metaphysical system developed by Alfred North Whitehead, and described in his book Process and Reality. Process philosophy believes that fundamental elements of the universe are occasions of experience. According to this notion, what people commonly think of as concrete objects are actually just successions of these occasions of experience. Occasions of experience can be collected into groupings; something complex such as a human being is thus a grouping of many smaller occasions of experience. According to Whitehead, everything in the universe is characterized by experience (which is not to be confused with consciousness); there is no mind-body duality under this system, because "mind" is simply seen as a very developed kind of experiencing.

Whitehead's philosophy resembles in some ways the concept of monads first proposed by Leibniz. However, unlike Leibniz's monads, Whiteheads occasions of experience are interrelated with every other occasion of experience that has ever occurred before. Inherent to Whitehead's conception is the notion of time; all experiences are influenced by prior experiences, and will experience all future experiences. This process of influencing is never deterministic; an occasion of experience consists of a process of prehending other experiences, and then a reaction to it. This is the process in process philosophy. Because no process is ever deterministic, free will is considered essential to the nature of the universe.

Whitehead gives God a special place in the universe of occasions of experience. God encompasses all the other occasions of experience but also transcends them; thus Whitehead embraces panentheism. Because free will is inherent to the nature of the universe, God is not omnipotent in Whitehead's metaphysics. God's role is to offer enhanced occasions of experience. God participates in the evolution of the universe by offering possibilities, which may be accepted or rejected.

Whitehead was influenced by the ideas developed in the early 1900s by French Jewish philosopher Henri-Louis Bergson. Bergson was awarded the Nobel Prize for Literature in 1927.

Process philosophy later served as the inspiration for a process theology.

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