What does it mean to be a skeptic? The meaning is obvious when someone says “I’m skeptical about X”.  Substitute for X any item from the list: alternative medicine, the landing on the moon, global warming, the sincerity of a particular politician, the existence of sincere politicians, or the US citizenship of Barack Obama. But what does it mean to adopt skepticism as a philosophical or intellectual attitude? Not skepticism about X, but skepticism period.

Take for example CSI. No, not the television series where übercops search for evidence on crime scenes, subject it to rigorous examination, interrogate suspects, raid their homes, engage in neck-breaking car chases, bare-knuckle fighting and spectacular shootouts while cracking witty jokes.  Thirty to fifty minutes later (depending on the number of commercial breaks), the crime is solved and the perpetrator arrested (or killed). Not that CSI.

I am talking about the Committee for Skeptical Inquiry, formerly known as CSICOP[1] (Committee for the Scientific Investigation of Claims of the Paranormal). CSI’s mission is “to promote scientific inquiry, critical investigation, and the use of reason in examining controversial and extraordinary claims”. Similar organizations exist all over the world, many of them  using the word ‘skeptic’ or a derivative in their names (for a nice overview of skeptical websites and organizations, go to this page on skepsis.nl, the Dutch skeptics). Historically, many of those organizations focused on examining the evidence for “claims of the paranormal”, such as telepathy, remote viewing, astrology, etc. Gradually they came to widen their scope, and today they are the defenders of rationality in areas as diverse as alternative medicine, conspiracy theories, doomsday prophecies, creationism, Freudian psychoanalysis, flying saucers and supernatural miracles.

A typical reaction of opponents (usually believers in one or other of the above-mentioned ideas) has been to deride skepticism as a stubborn refusal to believe things that don’t fit the skeptics’ narrowly scientific worldview. Being a skeptic however, in spite of the word, does not amount to merely believing few things and doubting many. It’s a matter of what you believe, or more importantly, why you believe something.

For example, the 9/11 truthers don’t believe the World Trade Center buildings collapsed as a result of terrorist attacks. Though they can be said to be skeptical of al-Qaeda’s involvement in the tragic events, they are not skeptics in the unqualified meaning of the word. Creationism and its disguised successor Intelligent Design don’t accept Darwin’s theory of evolution, while skeptics defend it vigorously. Skeptics, just like creationists, believe one thing but not the opposite. What distinguishes skeptics are the reasons for believing what they believe.

Skeptics have a genuine interest in learning the facts. If the facts turn out to overturn their beliefs, they have no problem altering them. They just go where the evidence leads them, without trying to  bend the facts to their beliefs. They always heed astronomer Carl Sagan’s warning, though: “Extraordinary claims require extraordinary evidence”. Skeptics “do not reject claims on a priori grounds, antecedent to inquiry, but examine them objectively and carefully”[2]. As a demonstration of their openness and goodwill, but also of their confidence in science, some organizations offer generous prizes to people who can prove they have supernatural powers. The James Randi Educational Foundation offers as much as a million bucks. SKEPP, the Dutch-speaking Belgian skeptics, recently increased the stake of their Sisyphus prize to € 1 million, even surpassing James Randi’s offer (at current exchange rates).

Doubtful as they are about superstition and aware of the human propensity for prejudice, skeptics share an enthusiastic belief in science and rationality, while still acknowledging science’s limitations and the provisional nature of scientific theories.

Then you have that other variety of skepticism, which goes back much further in history. It is known as philosophical skepticism, or radical skepticism. Sextus Empiricus, to whom Nassim Taleb pays homage in The Black Swan, is one historical figure associated with that tradition. As beautifully recounted in Bertrand Russell’s History of Western Philosophy, the ancient Skeptics had little respect for received dogma, which is certainly a virtue. But their persistent doubt soon became a dogma in
its own right: dogmatic doubt. Skepticism in those days appealed to unphilosophic minds because, in a sense, it stood above the disputes among various schools of thought that all professed to hold the truth. However,

Skepticism was a lazy man’s consolation, since it showed the ignorant to be as wise as the reputed men of learning. […] The man of science says “I think it is so-and-so, but I am not sure.” The man of intellectual curiosity says “I don’t know how it is, but I hope to find out.” The philosophical Skeptic says “nobody knows, and nobody ever can know.”

–    Bertrand Russell: History of Western Philosophy, 1945

Observe the stark difference between the nihilism of the philosophical skeptic and the positive optimism of the modern scientifically minded skeptic. The former throws his hands in the air and surrenders to ignorance before he’s made any serious attempt at acquiring knowledge about anything. The latter’s attitude is much more constructive and productive. Maybe she will never find out why so-and-so, but if she doesn’t try, then for sure she never will. A healthy skepticism to whatever she discovers is absolutely necessary, but rejecting all knowledge is a totally sterile attitude. And also totally impractical. Why bother going home if you can’t be confident your house is still there?

To doubt everything or to believe everything are two equally convenient solutions; both dispense with the necessity of reflection.

–      Henri Poincaré, French mathematician and physicist

No doubt that impracticality is the reason why many of its proponents wear their cloak of radical skepticism to conceal a double standard: they advocate an extreme skepticism towards beliefs to which they feel hostile, but abandon all caution when it comes to their own convictions.  In fact, the word pseudoskepticism would be more apt to describe such a mode of thinking.

So the next time you hear a self-proclaimed skeptic warn investors of Black Swans, pointing to the dangers of drawing conclusions from finite samples, but recommending Black Swan investing (e.g. the barbell strategy) without providing evidence for its safety nor profitability, then you know you can take his alleged skepticism (and investment advise) with a grain of salt.