Extraordinary Claims and Extraordinary Evidence

by Dr Michael G Strauss

“Extraordinary claims require extraordinary evidence” is a phrase that was popularized by Carl Sagan but has its roots from at least the 18th century Enlightenment when the miracles of Christianity were being questioned by certain intellectual thinkers of the day. The most famous Enlightenment critic of Christianity was probably David Hume who wrote an essay called Of Miracles in 1748 where he states, “Suppose, for instance, that the fact, which the testimony endeavors to establish, partakes of the extraordinary and the marvelous; in that case, the evidence, resulting from the testimony, admits of a diminution, greater or less, in proportion as the fact is more or less unusual.”

At first this statement may sound reasonable. For instance, I am more likely to believe you if you tell me you had breakfast this morning than I would believe you if you told me that you levitated off the ground this morning without anything holding you up. But does the fact that I believe you if you say you did something ordinary and I don’t believe you if you say you did something extraordinary support the statement that “Extraordinary claims require extraordinary evidence?” Actually, it doesn’t. Although I may believe that you ate breakfast this morning, I must obtain supporting evidence if I want to actually determine whether or not that fact is true. If you have cleaned up your kitchen, such evidence may be hard to find. I might have to pump out the contents of your stomach, for instance to see what you ate and when you ate it. It is one thing to say that I believe you ate breakfast because it is an “ordinary” event, but it is quite another to actually find enough evidence to validate your claim. My point is that actual validation of any event requires sufficient evidence.

It seems to me there are two major categories of “extraordinary” claims that need to be considered. The first would be a claim that can be tested in a controlled environment, like if someone claimed to be able to predict the outcome of rolling a six sided die 90% of the time, or if someone claimed to be able to levitate at whim. Those kinds of miraculous paranormal assertions can be easily tested, and to my knowledge, have never been validated as true. But the second category of “extraordinary” claims, which would include the miracles believed by Christians to be true, are events that occured only once in the past, and can not be tested in a controlled environment. I can’t imagine any amount of evidence would convince Hume that such a miracle has occurred. He states, “A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined.” For this second case, I believe that the claim that “extraordinary claims require extraordinary evidence” is really just a presumptuous statement, and that no amount of evidence would ever convince the skeptic that a past single miraculous event occurred.


Dr Michael G Strauss: Extraordinary Claims and Extraordinary Evidence