In brief, the six principal plays in the denialist playbook are:
Doubt the Science
Question Scientists’ Motives and Integrity
Magnify Disagreements among Scientists and Cite Gadflies as Authorities
Exaggerate Potential Harm
Appeal to Personal Freedom
Reject Whatever Would Repudiate A Key Philosophy
The account of chiropractors' reaction to the polio vaccine is especially interesting.
Children were especially vulnerable, so parents watched anxiously for any sign of infection, often keeping them away from swimming pools, movie theaters, bowling alleys, anywhere where there were crowds and the dreaded microbe might lurk. Travel and business were sometimes curtailed between places with outbreaks, and public health authorities imposed quarantines on healthy people who may have been exposed, in order to halt the spread of the disease. In the first half of the 1950s, with no cure and no vaccine, more than 200,000 Americans were disabled by the poliovirus. The virus was second only to the atomic bomb as to what Americans feared most.
Then, on April 12, 1955, public health officials at the University of Michigan announced that a “safe, effective, and potent” vaccine had been found. This set off a national celebration that recalled the end of World War II. Church bells rang, car horns honked, people wept with relief. President Eisenhower invited the vaccine’s inventor, Jonas Salk, to the White House. In a Rose Garden ceremony, the former Supreme Allied Commander told the scientist in a trembling voice, “I should like to say to you that when I think of the countless thousands of American parents and grandparents who are hereafter to be spared the agonizing fears of the annual epidemic of poliomyelitis, when I think of all the agony that these people will be spared seeing their loved ones suffering in bed, I must say to you I have no words in which adequately to express the thanks of myself and all the people I know—all 164 million Americans, to say nothing of all the people in the world that will profit from your discovery.”
But, alas, not everyone joined the party and expressed such gratitude. One group in particular did not welcome the vaccine as a breakthrough. Chiropractors actively opposed the vaccination campaign that followed Salk’s triumph. Many practitioners dismissed the role of contagious pathogens and adhered to the founding principle of chiropractic that all disease originated in the spine. Just a few years after the introduction of the vaccine, as the number of polio cases was declining rapidly, an article in the Journal of the National Chiropractic Association asked, “Has the Test Tube Fight Against Polio Failed?” It recommended that, rather than take the vaccine, once stricken, “Chiropractic adjustments should be given of the entire spine during the first three days of polio.”
Opposition to the polio vaccine and to vaccination in general continued in the ranks such that even four decades later, long after polio had been eradicated from the United States, as many as one third of chiropractors still believed that there was no scientific proof that vaccination prevents any disease, including polio. That belief and resistance continues to this day, with some chiropractors campaigning against state vaccination mandates.