By this term, I mean the disciplines of science which rely upon evolutionary thinking as the backbone of their studies. In practice, this includes much of biology, geology, and astronomy. It doesn't include those areas which are primarily mathematics, and for which origins is irrelevant, or those who work in conservation science or ecological studies of present-day species. Practicioners of those disciplines may be evolutionists, but their work does not hinge on that theory. Evolution itself is considered to be indisputable by many scientists today.
Evolutionary theory assumes that the universe is undesigned.
More specifically, that the universe came into existence through physical reactions unaided by any outside intelligent force. Life then arose on our planet through chemical and biological processes, and life has continued to change its form over a long period of time through random mutation and non-random natural selection. Evolutionists believe that science and religion must not be confused with one another. They believe that natural processes are capable of explaining the existence of the universe and of life itself, and that subjects which appear designed are actually the work of natural processes.