Abstract

The term pseudoscience refers to a highly heterogeneous set of practices, beliefs, and claims sharing the property of appearing to be scientific when in fact they contradict either scientific findings or the methods by which science proceeds. Classic examples of pseudoscience include astrology, parapsychology, and ufology; more recent entries are the denial of a causal link between the HIV virus and AIDS or the claim that vaccines cause autism. To distinguish between science and pseudoscience is part of what the philosopher Karl Popper referred to as the demarcation problem, a project that has been dismissed by another philosopher, Larry Laudan, but that keeps gathering much interest in philosophers, scientists, educators, and policymakers. This entry provides the basics of the debate about demarcation, as well as a brief discussion of why it is of vital importance not just intellectually but for society at large.