Few concepts are more poorly understood or more abused than skepticism. The best example of this abuse is to attribute the moniker of "climate change skeptic" to those who ignore the overwhelming data concerning global warming.
The shortest definition of skepticism is "an attitude of doubting the truth about a claim or statement." Something a bit more meaningful would be "suspending judgment and applying systematic reservation about a claim or statement."
So why can't we rightfully call a denier a skeptic since he doubts or has reservations about the truth about climate change claims, which would at first glance meet the definition of skepticism? We shall see.
Michael Shermer, Executive Director of the Skeptics Society, has rightfully noted that "skepticism is not a position, it is a process." It is the application of critical thinking to evaluate the validity of an assertion. Saying that "I am a skeptic" has little meaning because that is a stance; more meaningful is a statement like, "I am open to accepting a claim if presented with sufficiently convincing evidence."
What we are talking about here, even though everybody uses the term skepticism, is actually "ordinary incredulity." We are not including here what is technically "philosophical doubt" -- a more formal version of skepticism, an intellectual exercise to deny the validity of an entire class of claims by positing that certain knowledge is not attainable even in theory. Yeah, I know, that is a little opaque. But we really do need to understand the distinction between ordinary incredulity and philosophical skepticism before we can nail down why deniers are not in fact skeptics. The best way I've come across is a review of the Truman Show and the Matrix as put forth in the Stanford Encyclopedia of Philosophy.
Truman is placed, without his knowledge, in a contrived environment so that his "life" can be broadcast on television. Truman comes across clues that something is wrong. In The Matrix, where everything is running as programmed by the machines, there is no possible way for the "people" in the matrix to determine that the world as experienced is only a "dream world" and not the real world (the world of causes and effects). The Truman Show is a depiction of a case of ordinary incredulity because there is some evidence that is, in principle, available to Truman for determining what's really the case; whereas The Matrix depicts a situation similar to that imagined by a typical philosophical skeptic in which it is not possible for the Matrix-bound characters to obtain evidence for determining that things are not as they seem (whenever the virtual reality is perfectly created). Put another way, the philosophical skeptic challenges our ordinary assumption that there is evidence available that can help us to discriminate between the real world and some counterfeit world that appears in all ways to be identical to the real world.
So from that we conclude that ordinary incredulity (what people typically call skepticism) arises when in principle doubt can be removed by discovering the truth of some claim or statement.
And here is precisely why climate change deniers do not have the high privilege of being called skeptics. No amount of data, no convincing evidence, and no degree of proof would ever convince a denier that climate change is real. Even in principle a denier's doubt cannot be removed because a denier is relying on faith rather than evidence to support his position. If doubt cannot be removed with new knowledge or advances in understanding, then that is not skepticism - it is just a form of religion.
Cynicism Is Not Skepticism
Offering a skeptical perspective is not cynical; in fact quite the opposite is true. Cynics doubt and mistrust not on the weight of evidence or lack thereof but on suspicions of underlying motivation. Cynicism can lead to the rejection of a claim but not to new discoveries, unlike skepticism which can lead to both.
Provisional disbelief is often mistaken as cynicism; the two are not equivalent. It is perfectly reasonable to start out unconvinced that humans are causing our climate to change. But that shifts to cynicism and faith-based opposition with the inability to modify that position in the presence of overwhelming evidence. What matters, independent of one's starting hypothesis, is the willingness to draw conclusions when a claim is confirmed "to such an extent that it would be reasonable to offer temporary agreement."
Skepticism is fully embedded in the scientific method: the application of systematic observation, reproducible measurements, and experimentation in order to gain new knowledge about and a deeper understanding of our physical and biological world. The entire reason for applying systematic observation is that we are open to but remain skeptical of any claim's validity until observation, reproducible measurements and experimental confirm or reject the claim.
Climate change denial is a form of cynicism and as such is the antithesis of skepticism; it is the closed-minded pre-determined rejection of any and all data that might validate the claim that our climate is changing, and the blind credulous acceptance of any unsubstantiated assertions that support the denial. Here is the bottom line difference between a denier and someone currently convinced the climate is changing: if presented with convincing contrary evidence that demonstrates the earth's climate is not warming, or is changing by natural cyclical variation alone, one who temporarily accepted that the earth is warming because of human activity would modify his conclusion based on this new knowledge. In contrast, no mountain of data demonstrating that humans are causing a changing climate would cause a denier to modify his conclusion. Skepticism demands an open mind and allows for and encourages the advancement of knowledge by seeking explanations of phenomena anchored in the natural world; faith-based denial is immune to modification.
A denier may come back and say that in fact those who claim the climate is changing are the ones with closed minds since they openly reject what deniers believe. But no, that is false equivalency; deniers could indeed make headway if they could present convincing data but the inverse is not true.
Open Mind, Gullibility and Conviction
We must not confuse an open mind with gullibility. A mind open to change in the face of convincing data is not equivalent to credulous acceptance of a claim absent of evidence. Nor can we confuse an open mind with lack of conviction. Climate change experts are secure in their conclusions based on overwhelming evidence across multiple disciplines, confirmed independently by thousands of scientists in hundreds of countries. They have no less an open mind because they are firm in their conclusion. With overwhelming evidence in hand the threshold for modifying one's temporary acceptance becomes ever higher. The threshold for change is elevated on the basis of accumulating evidence, not faith. We can confidently conclude, without being accused of being closed minded, that atoms are a building block of nature, that DNA contains the genetic code, and that the earth orbits the sun. Being highly confident about these statements is justified by incredibly precise measurements, reproducible observations and extraordinarily refined experimentation performed by tens thousands of scientists over decades or centuries. Yes it would be possible to overturn these conclusions with sufficiently convincing contrary data, but given the history leading to our understanding of these aspects of the natural world, that is not likely to happen. That does not make us closed-minded; it makes us firm in our convictions but open to being convinced otherwise by overwhelming data. Climate change deniers in contrast can never be otherwise convinced.
Deep Irony
Climate change deniers bring to the debate a deep irony and terrible hypocrisy that add another disturbing element beyond the important difference between cynicism and skepticism. We know that deniers demand more proof that the climate is warming even in the face of a growing body of accumulating evidence. We know too that while they demand such proof no quantity of date would ever be sufficient because the denial is not based in skepticism but in cynicism and faith. And yet. And yet this same demand for proof is conspicuously and gloriously absent when the question turns to patently false claims about fat-burning foods or a host of bogus promises relating to diet and nutrition, or the link between autism and vaccines, or the economic viability of nuclear power, or clean coal, or alien landings, or the Bermuda Triangle, or virtually anything that is not climate change. Only with climate change is such proof demanded; meaning we have the circumstance in which deniers reject a conclusion for which we have overwhelming evidence but accept wild claims for which there is none. Some significant number of Republicans, even if not a majority as sometimes reported, believes that Obama is a Muslim; where is the demand for proof? Such is the dangerous brew of faith stirred with cynicism in the absence of reasonable credulity.
There are no climate change skeptics; only faith-based climate change cynics.