Evolutionism is a family of ideas which affirm that
the universe and some or all of its parts have undergone
irreversible, cumulative changes such that the number,
variety, and complexity of the parts have increased.
Evolutionism is thus opposed to the belief that the
universe and its parts are eternally the same; or that
they have been the same since they were created; or
that they are now the same as they have been periodi-
cally in the past; or that they are emanations from a
higher and perfect source. If only living things are
included, theories of organic evolution result. These
theories may embrace accounts of human, mental,
moral, and cultural evolution. If nonliving things are
included, there result theories of physical evolution
which may embrace the earth, the solar system, and
the spatiotemporal cosmos. If what is included is the
universe as a whole, or everything that is held to be
real, metaphysical theories of evolution result. Hence
many differences occur within the one family of ideas.
Early theories tend to be simple, vague, and specula-
tive. Later theories, particularly when given a scientific
formulation, are more intricate, exact, and verifiable.
There are many disagreements, however, about such
issues as the origin, character, and causes of evolu-
tionary processes. In the present article some of the
main stages in the history of this family of ideas will
be discussed.
