Philosophy 101 with Plato’s Republic was my introduction to the concept of inductive reasoning and later anecdotal evidence. My earliest brush with inductive reasoning was the statement, “This is a leaf… All leaves are like this.”

Obviously, part of this is true, but the most important assertion is not — that all leaves are alike.

The definition of inductive reasoning since has grown and the dictionary insists that, “Inductive reasoning (as opposed to deductive reasoning or abductive reasoning) is reasoning in which the premises are viewed as supplying strong evidence for the truth of the conclusion. While the conclusion of a deductive argument is certain, the truth of the conclusion of an inductive argument may be probable, based upon the evidence given.”

A kissin’ cousin of inductive reasoning for me has been something we know as anecdotal evidence, a very powerful tool in the seedy world of marketing and advertising and equally powerful in false political arguments.

Perhaps the best example of anecdotal evidence is advertising for miracle diets. Testimonials from individuals, particularly celebrities can be effective in peddling products that may or may not work. “I lost 50 pounds in six weeks… you can too!”

Anecdotal evidence tells a story that while true may not prove anything at all, particularly causation.

About 25 years ago I read a true story in a Scientology journal about a woman whose life was ruined by Xanax, “a powerful psychotic drug,” yet it has been one of the most prescribed medications in the U.S. Her life was ruined, but its doesn’t mean everyone else’s will be.

A recent article in the Scientific Journal indicated, “The recent medical controversy over whether vaccinations cause autism reveals a habit of human cognition—thinking anecdotally comes naturally, whereas thinking scientifically does not.

“On the one side are scientists who have been unable to find any causal link between the symptoms of autism and the vaccine preservative thimerosal, which in the body breaks down into ethylmercury, the culprit du jour for autism’s cause.

“On the other side are parents who noticed that shortly after having their children vaccinated autistic symptoms began to appear. These anecdotal associations are so powerful that they cause people to ignore contrary evidence: ethylmercury is expelled from the body quickly (unlike its chemical cousin methylmercury) and therefore cannot accumulate in the brain long enough to cause damage.

“And in any case, autism continues to be diagnosed in children born after thimerosal was removed from most vaccines in 1999; today trace amounts exist in only a few.

“The reason for this cognitive disconnect is that we have evolved brains that pay attention to anecdotes because false positives (believing there is a connection between A and B when there is not) are usually harmless, whereas false negatives (believing there is no connection between A and B when there is) may take you out of the gene pool.”

I am particularly alarmed by “friends” on Facebook who constantly present memes, pictures and videos, of people of color doing reprehensible things to innocent victims. Of course, these kinds of thing happen, but the person posting information about it clearly wants to paint people of color or Muslims in a bad light, even though the incidents are anecdotal and the perpetrators are in a small minority.

Regardless, using anecdotal evidence to sell you something or to persuade you to feel a certain way about other human beings is a scurrilous practice crafted by scoundrels who have nefarious intentions. So beware.