DIFFUSION THEORIESsingle, unified, deductively structured collection
of propositions, widely regarded by social scien-
tists as identifying the principal mechanisms of
diffusion that could be employed across all sub-
stantive areas. There are however, many distinct
collections of propositions, a few well-tested over
decades, that describe different diffusion phenome-
na in different content areas. Indeed, in the area of
innovation diffusion, Everett Rogers (1983) pro-
duced a formal theory that is broadly recognized,
often tested, and that has been adapted to other
content areas including disaster research and tech-
nology transfer. Part of the problem in formalizing
diffusion theories is that the concept does not
inherently specify content (rather a framework or
process to structure thinking). However, it cannot
be examined empirically without tying it to some
substance. That is, studies of diffusion focus on
something (a technology, idea, practice, attitude,
etc.) that is being diffused. Consequently, the re-
search on diffusion that would drive theory build-
ing has remained scattered in the literatures of
different sciences, and as such it is not readily
pulled together. These conditions do not facilitate
ready assembly of information that would encour-
age creation of a general theory of diffusion. Thus,
one must look to the growth of formal theory in
sub-areas, although Rogers (in press) has begun to
cross content spheres.
There are at least three traditions or theory
families that can be historically discerned in the
study of diffusion. Rogers (1983, p. 39) has point-
ed out that for many years these traditions re-
mained largely distinct, with little overlap and
cross-fertilization. Since the late l970s the level of
research and theoretical isolation has decreased,
leading to an enhanced awareness among the
perspectives and some integration of empirical
findings into more general theoretical statements.
The three theory families are: (1) cultural diffu-
sion; (2) diffusion of innovations; and (3) collec-
tive behavior.
CULTURAL DIFFUSIONThe earliest social scientific use of the term diffu-
sion is found in Edward Tylor’s (1865) treatment of
culture change. Anthropologists have long attempt-
ed to explain similarities and differences among
cultures, especially those that were geographically
adjacent. Tylor’s work on culture change first
proposed the notion of diffusion as a means of
explaining the appearance of similar culture ele-
ments in different groups and of understanding
the progressive alteration of elements within the
same group. As the twentieth century began, diffu-
sion arose as an alternative to evolution as a basis
for understanding cultural differences and change.
Evolutionists argued that cultural similarities prob-
ably arose through independent invention. Those
who embraced diffusion presented it as a more
parsimonious explanation, emphasizing that traits
and institutions could pass between groups by
means of contact and interaction.Historical Development. The English anthro-
pologists W. J. Perry and Elliot Smith devised the
most extreme position on cultural diffusion. These
scholars held that human culture originated in
Egypt and progressively diffused from that center
over the remainder of the earth. In Germany, Fritz
Graebner (1911) argued that critical aspects of
cultures—toolmaking, for example—originated in a
small number of geographically isolated societies.
This hypothesis formed the basis for culture circles
(‘‘kulturkreise’’), collections of societies sharing
similar cultures. Unlike British diffusionists who
emphasized tracking the movement of single cul-
ture elements, Graebner and others in his tradi-
tion focused on the dissemination of collections of
elements or cultural complexes.American anthropologists are credited with
developing a social scientifically workable concept
of diffusion. Franz Boas (1896) conceived of diffu-
sion as a viable mechanism for culture exchanges
among geographically adjacent areas. His view
figured prominently in the intellectual move away
from the deterministic view of diffusion proposed
by early British anthropologists. Alfred Kroeber
(1923, p. 126) and Robert Lowie (1937, p. 58)—
students of Boas—subsequently developed a posi-
tion called moderate diffusionism, which is currently
widely accepted in anthropology. This position
allowed for the coexistence of a variety of mecha-
nisms of change and transfer—independent in-
vention, acculturation, etc.—in addition to diffusion
in accounting for culture change and differentia-
tion. Clark Wissler (1929), a Kroeber contempo-
rary, established an empirical basis for culture
diffusion by identifying ten culture areas (regions
with similar cultural inventories) in North and
South America and the Caribbean.