The term monism comes from the Greek word meaning alone or single. While the term was originally used by German mathematician and philosopher Christian Wolff (1679–1754) to refer to views asserting either that everything is mental (idealism) or everything is material (materialism), monism has wider applicability today, claiming that the various things or kinds of things encountered in the world are somehow reducible to, derivable from, or explicable in terms of one thing (substantival monism) or one kind of thing (attributive monism). The substantival and attributive views are logically independent—e.g., Baruch Spinoza (1632–1677) affirmed the first while holding a plurality of attributes; Gottfried Wilhelm Leibniz (1646–1716) held the second while countenancing a plurality of substances.

Monism must be distinguished from pluralism, which asserts that there are various things or kinds of things. Monism must also be distinguished from dualism, which claims that there are only two basic kinds of things. Often, however, the term monism is used imprecisely to refer to any fundamental dichotomy in a philosophical or religious system (e.g., good and evil, soul and body, male and female). Of particular interest in the science-theology conversation are the apparent dualisms of mind and body, and God and universe.

A primary motivation for monism is ontological simplicity—a world in which there is one basic thing or kind of thing makes fewer ontological claims than one asserting the existence of many things or kinds. Explanation for the monist is homogeneous and coherent; it makes no appeal to entities of a different ontological type when framing its causal stories. Moreover, the assumption of monism (particularly of physicalist variety) has been enormously fruitful. On the other hand, pluralism is motivated by the apparent multiplicity of things and kinds, and the desire to avoid purchasing simplicity at the expense of real complexity. A further advantage of monism is that, unlike pluralism, it does not need to offer an account of a relation that supposedly conjoins fundamentally disparate kinds.

In addition to materialist (physicalist) and idealist monisms, there is also neutral monism and anomalous monism. The first claims that both mental and physical phenomena are manifestations of an underlying neutral stuff. Spinoza and Bertrand Russell (1872–1970) are associated with this position. The second, advanced by twentieth century philosopher Donald Davidson, holds that while every mental event is token identical to some physical event, mental properties can nonetheless not be reductively identified with physical properties. Because mental properties are individuated holistically according to criteria of coherence, rationality, and consistency which, as Davidson notes, "have no echo in physical theory" (p. 231). Although all particulars are physical (physicalist monism), the incommensurability between mental and physical properties requires a property dualism.

Both substance and property dualism are of interest in the science-theology discussion. For example, most would claim that substantival and attributive monism are both incompatible with the substance dualism of divine and worldly stuff (or creator and created stuff) that theism presupposes. Others have suggested that since God can be understood immanently, a dualism of divine and worldly properties is compatible with a monistic ontological physicalism. The question for the science-theology conversation is whether God-universe or mind-body property dualism coupled with physicalist monism has the resources to avoid reductive explanation, and thus successfully to ground an ontology of the mental and the divine.

See also DUALISM; MATERIALISM; NATURALISM; PHYSICALISM, REDUCTIVE AND NONREDUCTIVE; PLURALISM

DENNIS BIELFELDT