Many philosophers have come to believe there is no single criterion by which one can distinguish between a science and a pseudoscience. But it need not follow that no distinction can be made: a multifactorial account of what constitutes a pseudoscience remains possible. On this view, knowledge-seeking activities fall on a spectrum, with the clearly scientific at one end and the clearly non-scientific at the other. When proponents claim a clearly non-scientific activity to be scientific, it can be described as (...) a pseudoscience. One feature of a scientific theory is that it forms part of a research tradition being actively pursued by a scientific community. If a theory lacks this form of epistemic warrant, this is a pro tanto reason to regard it as pseudoscientific. (shrink)