Tips On Arguing: Argument from Ignorance

Inquiry:

In Latin (and formal logic), this is known as the “argumentum ad ignorantiam.” There are two basic types, both founded on a lack of evidence.

The first says that because there is not enough evidence to prove something, it can’t be true. The obvious mistake here lies in the assumption that no further evidence will ever be found.

There is a perfect example of this in ancient Greek philosophy, when the philosopher Democritus speculated that all matter was made up of pieces floating in space that were all basically the same, but fit together in different ways to make up everything in the world. This view lost prominence for many centuries, because few could imagine things like water and fire being composed of the same materials. But by 1808, enough scientific research had been done for chemist and physicist John Dalton to put forth the first atomic theory (the word “atom” came directly from Democritus’ ideas).

The lesson? You can never say that something is impossible – just unlikely.

The other type of argument from ignorance states that because there is not enough evidence to prove one hypothesis, another hypothesis is automatically true.

This form of argumentum ad ignorantiam has led to some of America’s darkest moments. In the 1950’s, Joseph McCarthy began accusing many high-profile citizens as being communist sympathizers or spies.

In his 1995 book, Arguments from Ignorance, University of Winnipeg Philosophy Professor Douglas N. Walton explained why McCarthyism failed the litmus test of logic: “You were presumed guilty, once accused, and the burden then lay on the accused party to provide evidence of being innocent.” McCarthy sometimes openly said that his reason for making an accusation was the fact that he had no evidence to suggest that the person was not in league with the communists.

This is the reason that the argument from ignorance can be so dangerous. The fears that allowed McCarthyism to flourish overshadowed rational considerations for both the general public, as well as some government officials. As Walton notes, this kind of negligence “can be very convincing for a time, with devastating effects on affected individuals.”

The lesson? Just because there’s no evidence for one thing doesn’t necessarily mean another thing is true.

Jenny McCarthy on Autism Awareness?

Journey:

TIME magazine recently posted an article in its Health & Science section in which Jeffrey Kluger, one of the science writers, interviewed Jenny McCarthy about her opinions on autism and vaccines. Though the interview did reveal a few things about McCarthy, this reporter did not do enough to confront the dodged questions when they occurred. What follows is an open letter written by me to him and TIME in response to the published piece:

Dear Mr. Kluger/TIME Staff:

I had been considering renewing my subscription to your magazine, until I came across a recent interview published on TIME.com titled "Jenny McCarthy on Autism and Vaccines" that was published in your Health & Science section.

Although you asked a few tough questions of McCarthy, you completely failed to follow up on some of her responses, many of which were ill-informed, used faulty logic, or were just plain sick. Not only did you let her get away with terrible and dangerous lies, but you printed them in a section of your magazine that gives her misinformation the same implied weight as a doctor or expert.

McCarthy apparently believes that "some diseases," such as polio and measles, need to make a comeback in order to protect children from autism. Does she realize that millions of people have died of these diseases throughout history? Would it be better to have a child die than to have a child live with autism (not that this is a choice that actually needs to be made)? Why was this reasoning not questioned?

McCarthy did not answer your question about the postulation of scientists who note that we're diagnosing autism differently. Instead she referred to schoolteachers and principals as her "experts." You ought to have pointed out that these people do not diagnose autism, and that their "data" is almost entirely anecdotal.

You let her get away with the "moving the goalpost" fallacy when you asked her about mercury in vaccines and she replied that she was now concerned about "aluminum and other toxins." You could have countered this easily by simply asking what it would take for her to feel that vaccines were "safe." Or you could have asked her what these toxins were and what studies she knew of that showed that they were unsafe.

These are just a few examples.

It's extremely important that journalists practice critical thinking when interviewing their subjects, and that they don't allow the "unbiased" rule to get in the way of calling an interviewee's bluff - especially when it comes to issues that can have profound impacts on the lives of millions of people.

I expect better of TIME, and better of you, Mr. Kluger. I truly hope that you will not allow your science articles to become the tool of anti-scientific propaganda in the future. Until that happens, I'll be looking for my news elsewhere.

Sincerely,
Brandon T. Bisceglia.

Here are other links about Jenny McCarthy:

Jenny McCarthy, Indigo Mom
Wikipedia - Jenny McCarthy
Generation Rescue - McCarthy's and main man Jim Carrey's "Autism Awareness" Site
Medical Newsday - Reasearcher Says No Proven Link Between Vaccines and Autism
U.S. Department of Health & Human Services - The Effectiveness of Vaccines
CDC - All About Autism and Vaccines