It seems the word skepticism has taken on a new meaning in the past several years. I have heard it tossed about frequently of late, both in a positive and negative light. There are skeptical societies,^1,2 two skeptical magazines,^3,4 and many skeptical podcasts⁵ and blogs,^6,7 all of which promote networking among skeptics and keep us informed about the latest bits of pseudoscience. Yet, the willingness to believe the improbable remains a constant in our society, and the credulous often frown upon skeptical people. So, what does skepticism really mean, and how does it help us as scientists and as humans?

Scientists are admirable skeptics when it comes to science since we learn early on how to think critically about the research that makes its way across our desks. This does not mean that we assume everything to be false until it has been definitively proven—irrefutable evidence is exceedingly rare. Instead, we let the scientific method guide us. It is a blueprint for designing experiments, but it also helps us to analyze the validity of experiments performed by others. We begin by asking what is the proposed hypothesis, and then decide if the presented data agrees with it. Agreeable data does not prove a hypothesis—it merely supports it, and we must look deeper to determine how well-supported it is. Were the proper control experiments performed? Does previous research offer more evidence? If these conditions are met, one should still hold out for the possibility that contrary evidence may some day come along. Therefore, our conclusions are always pending further experiments, and repeatability is often critical for scientific ideas to gain a foothold in the community.

Not all evidence is created equal. One well-designed experiment outweighs any number of poorly planned studies. Frequently, a paper is published that finds one reasonable conclusion, only to have it contradicted by a later report. In these cases, we weigh the evidence from each study and conclude, in our own minds, which is likely to be true. These debates are rarely cut and dry, but in all cases the correct theory eventually floats to the top, so long as the scientific method is properly carried out. This is because it is based on logic and reason. Critical thinking is like a sieve for the truth. Sometimes it takes years, decades, or centuries, but the correct answer will always endure, while conclusions from poorly designed studies and flawed reasoning should eventually be filtered out.

This works for scientists because we assume that an explanation exists for every observation that we make. In some cases the explanation may be forever out of our reach, but we still assume that one is there. Logically, we must make this assumption or there is no point in experimenting at all.

For some reason, this logic occasionally breaks down when we leave the realm of rigorous science. In our everyday lives we come across reports of unexplained phenomena, conspiracy theories tossed about by our friends, commercials for remedies that have no basis in medicine, and psychics clamoring to tell our fortunes or speak to our deceased relatives. As human beings we may be evolutionarily predisposed to believe in these notions, and our first reaction is usually to accept the premise. As scientists, we should avoid this and apply the same critical thinking skills that we use to assess the validity of research, and that is the heart of skepticism.

On the surface, the word skepticism seems to be purely negative—“you’re a skeptic? So… what? You don’t believe in anything?” Skeptics aren’t nihilists; it’s merely a convenient word that describes our appreciation for critical thinking, logic, and reason. We expect a scientific explanation for everything that we come across in the natural world. An important piece to skepticism, one that is often ignored, is that we must logically admit the possibility for every testable explanation to be true, no matter how unlikely it may be.

This is why the scientific method and skepticism are such elegant notions. We adapt our beliefs to fit the evidence. This may sound wishy-washy, but it is not. The alternative is to believe in something in the face of contrary evidence. This is the difference between a belief and an ideology—ideologues will never adjust their thinking. Blindly adhering to an ideology is never a good idea in science, and the same is true in our everyday lives. If the evidence shows that homeopathic cures have no effect on the common cold, then a skeptic is $10 richer than someone who practices homeopathy by purchasing a $10 dollar cure and no less likely to catch a cold.

There are many, many examples of occasions where we are justly served by skepticism, but I will not belabor this now. The main point I am hoping to get across is this: skepticism is a methodology that is firmly based in science. Indeed, the most useful tool for a skeptic is one that is familiar to all scientists. Occam’s Razor states that the answer that makes the fewest assumptions is the most likely to be true.⁸ It seems like such a simple notion, but there is a subtlety to it that we often overlook. At the heart of this principle is the use of evidence to determine the likelihood of a hypothesis. One thing is not inherently more likely than another—we subconsciously determine the likelihood upon weighing the strength of the evidence for both sides. For example, if a stranger walks up to you and correctly tells you in which city you were born, it is much more likely that it was a lucky guess (or cheating was involved) than that he has psychic powers. On the other hand, if he names the birthplaces of 20 randomly chosen people in a well-controlled situation, Occam switches sides and we must conclude that the most likely explanation is that this person is a bona fide psychic. Of course, such tests have been performed many times and the former conclusion holds firm.

This malleability of thinking shows that there is nothing inherently negative about skepticism; it is intrinsically objective. Unfortunately, skepticism is not a quality that we are born with, and objectivity is difficult for us to maintain. We scientists are armed with the ability to think critically when we are confronted with dubious scientific claims, but only because we have trained ourselves to do so. We still struggle with this in our non-scientific lives, and we must train equally hard to achieve it.

If this primer to skepticism has piqued your interest and you would like to learn more, feel free to contact me at , or visit the Web pages for The Skeptical Society, the New York City Skeptics, or any of the other sites listed below.

References:

¹ http://www.skeptic.com/

² http://www.nycskeptics.org/

³ http://www.skeptic.com/the_magazine/

⁴ http://csicop.org/si/

⁵ http://www.skepticality.com/index.php

⁶ http://www.theness.com/neurologicablog/index.php

⁷ http://www.sciencebasedmedicine.org/

⁸ Ariew, R (1976). Ockham’s Razor: A Historical and Philosophical Analysis of Ockham’s Principle of Parsimony

⁹ http://www.randi.org/joom/