\Du"al*ism\, n. [Cf. F. dualisme.]
State of being dual or twofold; a twofold division; any
system which is founded on a double principle, or a twofold
distinction; as:
(a) (Philos.) A view of man as constituted of two original
    and independent elements, as matter and spirit. (Theol.)
(b) A system which accepts two gods, or two original
    principles, one good and the other evil.
(c) The doctrine that all mankind are divided by the
    arbitrary decree of God, and in his eternal
    foreknowledge, into two classes, the elect and the
    reprobate.
(d) (Physiol.) The theory that each cerebral hemisphere acts
    independently of the other.
          An inevitable dualism bisects nature, so that each
          thing is a half, and suggests another thing to make
          it whole.                            --Emerson.