Mark Hoofnagle

Mark Hoofnagle is an American surgeon, skeptic and blogger known for his commentary on the phenomenon of denialism. He earned his M.D. as well as a Ph.D. in physiology from the University of Virginia, and is a graduate of the general surgery residency program at the University of Maryland. Hoofnagle's "denialism blog" is hosted by ScienceBlogs, and he also runs the website denialism.com jointly with his brother Chris.

In his overall summary of denialist positions — whether regarding global warming, evolution, vaccines, HIV/AIDS, 9-11 or anything else — Hoofnagle describes denialism as being defined by "the employment of rhetorical tactics to give the appearance of argument or legitimate debate, when in actuality there is none", identifying five main tactics used by denialists: conspiracy theories, cherry picking, false experts, moving the goalposts and general logical fallacies. He contends that denialist positions almost always degenerate into conspiracism, because "…denialist theories that oppose well-established science eventually need to assert deception on the part of their opponents to explain things like why every reputable scientist, journal, and opponent seems to be able to operate from the same page." He's also written a how-to-guide on being a crank scholar.

Mark Hoofnagle is responsible for coining the useful phrase "crank magnetism".