There has always been confusion and disagreement about the nature of the te
rms archetype and complex in Jungian circles, not to mention non-Jungian on
es. Another ongoing concern is whether Jung's concept of the archetype and
complex can be justified in terms of current scientific research, most nota
bly that of neurophysiologists and others interested in the brain and consc
iousness. This paper proposes a theory of the formation of complexes, namel
y, that they are created through self-organization within the brain/mind. S
elf-organization is a process typical of large complex systems, and is gene
rally accepted to operate within the brain and to be important in its funct
ioning. Examples of self-organization in biology are related to the psychic
processes that form the complexes. It is then natural to define the archet
ype in terms of the complex, and the authors propose a definition of the ar
chetype as an equivalence class of complexes. On this view, the archetype i
s an emergent property of the activity of the brain/mind, and is, appropria
tely, defined at the level at which it emerges. This definition is in line
with the original development of Jung's ideas, in that he derived the conce
pt of the archetype from his earlier discovery of the feeling-toned complex
.