The Richard Hoagland of medicine, Joseph Mercola is an osteopath and a frighteningly popular alternative medicine guru and (more or less) cult leader. He advocates and takes seriously more or less any idiotic crackpot or anti-science idea he comes across, including but not limited to flu-denialism and anti-vaxx – even going so far as to work with Barbara Loe Fischer. He has claimed that modern medicine kills more people than it helps, that (consequently) BigPharma is really involved in a conspiracy to kill you/prevent you from accessing the real remedies, that the Pill is dangerous, that “toxic metals in vaccines and dental fillings” is the cause for a wide variety of ailments, that your shampoo is really dangerous, and that statin drugs are dangerous. He promotes, however, Gary Craig’s Emotional Freedom Technique.
His website (no, you don’t get a link) contains most branches of pseudoscience, all major sorts of crankery, every logical fallacy ever committed by man (some good ones in this), dishonesties and smearing. He claims to be uninterested in profit, but makes a lot of it from selling all sorts of bullshit remedies at a steep price. His trust in the naturalistic fallacy suppresses any real science or scientific evidence he may come across. His dietary advice adds random assertions to the naturalistic fallacy, and is in conflict with any advice given by serious organizations (rather, he thinks, people should eat … the products he sells). He also – obviously – peddles homeopathy (the piece commented on in this link was written by Amy Lansky and endorsed by Mercola) and the thoroughly debunked raw-milk idiocy (the idiocy here is pasted on pretty thickly).
Despite his denialism and anti-science stance (or because of it) Mercola has many supporters, especially among the delusional, the paranoid (whose distrust of government is so entrenched that they trust the word of any non-government-affiliated crackpot), New Agers (who are generally both) and other critical-thinking-challenged groups. He has even attempted to pander to the religious through the ridiculously distortive screed discussed here. He is pretty good at following the fads and exploiting current trends and fears, and has been voted the no.10 “game changer” by readers of the Huffington Post, which tells you more about HuffPo’s health section than Mercola. More here.
His popularity stems from a combination of idiots, his authorship of two New York Times bestsellers (“The No-Grain Diet” (with Alison Rose Levy) and “The Great Bird Flu Hoax”), and a stinking pile of other books. He has also been featured on several of the more woo-friendly TV shows, including Mehmet Oz’s show.
Diagnosis: Looking more and more like a cultmaster, Mercola is an addle-brained and chronically misguided woo-meister. He is severely dangerous, however, insofar as he has managed to gather a frighteningly substantial herd of followers.