We should usually defer to experts in their fields. If 99 percent of mechanics tell me my fuel injector needs fixed, I should have them undertake this repair. I should not seek that one outlier because I think the rest are beholden to Big Auto or because an online echo chamber convinced me my injector just needs sprinkled with a mix of high-octane gasoline and wheat grass.

But this deference only applies when persons are speaking to their areas of expertise. If 99 percent of those mechanics recommended investing in a certain equity fund, that suggestion would be much less persuasive. Following this advice would be committing the Appeal to Authority fallacy, which occurs when someone treats a person’s authority in an unrelated field as validation of something they believe in.

The website “Logically Fallacious” used the example of citing the Pope as proof that bread and wine turns into the body and blood of Christ when placed in a parishioner’s mouth. The Pope is an expert on matters related to the Catholic Church, but that doesn’t mean me knows anything special about chemistry, especially concerning an untested concept that would be at work were there any truth to transubstantiation.

Perhaps the most widespread case of this fallacy is the notion that Vitamin C will prevent or cure colds. This is based on a pronouncement by Linus Pauling, a world class chemist who won the Nobel Prize in 1954. He also did pioneering work in molecular biology and won the Nobel Peace Prize in 1962, making him one of only two persons to win a Nobel in two categories. New Scientist listed his as one of the top 20 scientists of all time.

When he touted the benefits of Vitamin C for fending off colds, believers presented these credentials as evidence for his position. But by venturing into anatomy & physiology, Pauling was going beyond his area of expertise. There’s nothing wrong with that, but support for his position needs to be based on the evidence for it, not on the fact that he won Nobel Prizes in unrelated fields.

Pauling exhibited two traits common to alternative medicine proponents: Subjective validation and an emphasis on anecdotes. After he was diagnosed with Bright’s disease, he began following a low-protein, no-salt diet augmented with vitamin supplements. He felt better after doing so, but rather than calling for this to be investigated via the Scientific Method he had used so successfully in his career, he announced that mega-vitamin therapy could cure sickness. Pauling’s observation that he felt better would have been a fine starting point – observation is the first step in the Scientific Method. But Pauling jumped straight to asserting the existence of a new field, “orthomolecular medicine.” This is the idea that varying the concentration of substances in the body can prevent and treat disease.

Dr. Paul Offit, one of the country’s foremost pediatricians, said Pauling’s unsubstantiated assertions, combined with his exalted position, made him “arguably the world’s greatest quack.”

Pauling earned this label with such positions that heart disease patients should forsake prescription drugs and surgery for lysine and vitamin C. While starting with colds, he continually expanded his list of illnesses he believed could be influenced by orthomolecular therapy and even suggested it could treat mental conditions. Quack quack.

While he published some studies that seemed to support his views, other scientists were unable to replicate them. Two of his studies centered on groups of 100 allegedly terminal cancer patients, with a claimed result that vitamin C overloads had increased survival as much as fourfold. A re-evaluation of this claim showed that the two groups were not comparable since the group plied with mega-doses of vitamin C was healthier when the study began.

This is typical of the findings that research Pauling’s claims. In an interview with NPR, endocrinologist Marvin Lipman, said, “There have been at least 20 well-controlled studies on the use of mega doses of vitamin C in the prevention of colds, treating the duration of colds, and treating the severity of colds, and in none has there been any good evidence that vitamin C in mega doses does anything.”

There are no properly-conducted clinical trials that suggest vitamin C will prevent a mild affliction like hay fever, a serious condition like cancer, or any malady in between. Some persons think that since some Vitamin C is good, lots of it must be great. But some studies suggest a small amount of beer can have health benefits and that’s no reason to suspect that three cases a week would therefore be extra beneficial.

With regard to Pauling’s cancer hypothesis, the Mayo Clinic conducted three double-blind studies involving a total of 367 patients in late stages of the disease. The studies found that giving patients 10,000 milligrams of vitamin C was no more effective than a placebo.

Pauling himself took between 12,000 to 40,000 milligrams every day before dying of, you guessed it, cancer. His ad hoc reasoning for this intensely personal failure of his hypothesis was that he would have gotten the disease earlier without the vitamin C overdose. This thinking means proponents always have an out. If no cancer develops, the treatment worked. If cancer does not develop, the patient failed to take enough of the cure.

Of course, vitamin C is still vital to good health. And because people are unable to synthesize it endogenously, we need to get it from outside sources. Fruits are better for this than supplements because our bodies absorb vitamins from food more efficiently. I know this because my mechanic told me.