An old debunker’s adage goes (in various iterations), “You can never be too skeptical.” Lately, largely because of my run-ins with “skeptics” of evolution, I’ve become increasingly convinced that this slogan is fundamentally flawed. Consider, for example, what happens when a predisposition towards skepticism leads one to doubt a consensus view in the scientific community, or to pooh-pooh a possibility that many leading scientists consider highly likely. The skeptical impulse may be valuable, but taken to extremes, it can lose its usefulness and even lead to perverse outcomes.
Examples of this phenomenon abound. As a case in point, take a recent Scientific American column by Skeptics Society director Michael Shermer on the possibility of human life extension. Shermer basically slams all the various routes that scientists and visionaries have proposed for extending human life or even achieving immortality, grouping them under the following headings: “Virtual immortality,” “genetic immortality,” “cryonics immortality,” “replacement immortality,” and “lifestyle longevity.” But in his inclination towards skepticism, I think Shermer has lumped together fringe ideas about living forever with the relatively mainstream idea that significant human life extension may someday be possible.
Shermer is right to dismiss the concept of immortality in its various speculative guises. Even if we could entirely prevent our bodies from aging, perhaps by replacing parts one by one (Shermer’s “replacement immortality” example), we would all eventually succumb to freak accidents, like car wrecks. Nevertheless, laughing at immortality is very different from poking fun at the modest idea of lifespan extension through pharmaceutical inventions (Shermer’s “lifestyle longevity").
There are lots of cranks out there pushing unproven anti-aging remedies today. And as Shermer rightly notes, leading gerontologists have issued statements condemning such quackery. But many of those same scientists think we will be able to slow or even reverse human aging in the relatively near future. As I know from reporting on the science of life extension for almost a year now, a broad range of respectable opinion exists on this question. The most bullish gerontologists think we’ll be able to reverse mouse aging within ten years and succeed in humans not long afterwards. Then comes a larger group of scientists who think outright age reversal won’t work, or shouldn’t be tried first, but that human age retardation, which has already been achieved in some mammals through caloric restriction, might happen through the creation of caloric restriction mimetic pills or other drugs. (No one seriously believes that we’ll ever be able to stop eating so much.) Finally, the most pessimistic gerontologists, including the famed cell biologist Leonard Hayflick, doubt that either age reversal or age retardation will be possible—period.
I myself don’t have a view as to who’s right; I’m not qualified to make such a scientific determination. But as an experienced observer, I can safely say the following: Given this range of views among scientists, it’s foolhardy to dismiss human life extension at this point. And I’m not the only one who thinks we need to weigh this possibility carefully. Ethicists have already begun calling for more debate about how life extension would reshape individual lives and our societal institutions. The President’s Council on Bioethics just dedicated an entire report chapter to the question.
So when it comes to life extension, it’s definitely possible to be took skeptical. Something analogous can be said about another scientific area, this time one that’s far more politicized. As you may have already guessed, I’m talking about climate change.
If it’s unwise to take a knee jerk skeptical position about something many smart scientists think will happen (life extension), it’s even crazier to deny something that the overwhelming majority of scientists think is already
happening. Granted, I fully understand that a small minority of scientists, like Richard Lindzen, still deny that humans are causing climate change through the burning of fossil fuels. These scientists should certainly carry on being skeptical, at least so long as they believe in their own conclusions. But the rest of us ought to recognize that climate science has become increasingly robust over the past decade, and that the scientific community has increasingly spoken with one voice on this issue, even if some uncertainty remains about the extent of the problem.
Let’s go over a few facts in order to show that this is so. In early 2001, the Intergovernmental Panel on Climate Change (IPCC), a body comprised of over 2,500 scientists that’s the world’s leading authority on global warming, released its third major assessment of the issue. The IPCC concluded that humans are responsible for global warming and that this poses serious future risks. Now, for obvious reasons, this report posed a problem for the Bush administration, which quickly sought a review of the IPCC’s findings by the National Academy of Sciences (NAS). Given the IPCC’s lengthy and thorough process, this seemed a rather redundant effort to many. Sure enough, the NAS panel quickly confirmed the IPCC findings, adding still more force to the weight of scientific consensus.
Given this, anyone wishing to challenge the heavily reviewed conclusions of the IPCC and NAS has to overcome a rather staggering burden of proof. That’s not to say it can’t be done. But for the moment, it hasn’t, which means that adopting a skeptical stance towards climate change in the face of overwhelming scientific consensus can hardly be considered the most defensible position. Instead, I would hazard, it amounts to an abuse of skepticism.
When you think about it, such abuses have always been with us. Tobacco companies tried to make us “skeptical” of the link between smoking and disease. Other corporate interests have challenged whether toxic substances like lead and asbestos are really as dangerous as scientists claim. Anti-evolutionists themselves adopt a stance of skepticism when it comes to Darwin’s theory, arguing that natural selection could not have produced complex organs like the eye.
The reason we’re so vulnerable to abuses of skepticism is that it’s extremely hard to ever say that scientific conclusions are absolutely certain—much less to label scientific dissent a bad thing. After all, it’s certainly possible that 2,500 IPCC scientists might have made the same mistake. And if so, we would want someone to point that out. Still, the prevailing view on climate change has gone through repeated challenges in the court of scientific opinion and emerged in its current form. If we really wish to discard this consensus position, then in some sense we’re opting to discard the scientific process itself.
And that, finally, points to a way of determining when skepticism has gone too far and outlived its usefulness. In order to be responsible and useful, skepticism must respect the basic scientific process, rather than seeking to undermine it. It’s one thing to doubt. But it’s something else altogether to undermine the best mechanism we have at our disposal for knowing anything.