The lonely life of skeptics and the end of science

I like the word "skeptic," as in someone who habitually doubts accepted beliefs. My favorite skeptic of all time is David Hume, who talked about "positive skepticism," meaning that a skeptic is not a curmudgeon who simply rejects other people's opinions out of spite, but rather a careful thinker who accepts notions in proportion to the available evidence. Consequently, a good skeptic is not dogmatic, but on the contrary ready to change his position whenever warranted.

Nevertheless, I am constantly reminded of how naturally despised skeptics are, simply because they have a tendency to question people's (mostly irrational) cherished beliefs, an annoying (to most) habit of probing beyond the superficial reasons people often give in support of their half-baked ideas.

I was reminded of this during my recent trip to Cambridge for a scientific meeting. During a post-lunch break over (awful) coffee, I was engaged in a pleasant conversation with three really smart colleagues, all of them biologists, with an excellent training in statistical analysis and a host of published papers were they obviously demonstrated their abilities as researchers, logical thinkers, and -- especially -- their careful attention to the importance of argument backed by sound empirical evidence.

Right, until, of course, the conversation somehow wandered over philosophical territory. I don't recall exactly how it happened, but we began to talk about the possibility of the so-called "end of science." Much has been written about this, and most of it is rubbish. But the basic idea, I thought, is undeniably sound: science is about asking big questions concerning how the world works; there are a limited number of such questions; moreover, human beings are epistemically limited (meaning that there are limits to what we can know, given our finiteness, availability of resources, etc.); ergo, one of these days science will end in the sense that we will either have an answer to all the big questions (e.g., consciousness, origin of life, evolution, fundamental structure of matter, etc.), or we will run into some questions for which our epistemic limits will never be overcome (possible examples include what was there before the big bang, the possibility of parallel universes, etc.). Everything else will be stamp collecting, or seeking solutions to local puzzles that may be practically important, or even mildly interesting, but will not constitute big questions.

Wow, did that sort of reasoning ruffle some of my colleagues' feathers! The first argument against the end of science was that the universe may be infinite, and so would the number of questions we could ask. This is such a philosophically naive chain of reasoning that it is hard to believe it was proposed to me in all seriousness by an eminent biologist. First, of course, the universe may very well not be infinite (this is an empirical question). Second, there are some mathematical models that depict the universe as without boundaries (and therefore "infinite" in some sense) and yet limited, for example shaped like a donut. Third, and most importantly, the finiteness of the universe has nothing logically to do with the finiteness of the number of big questions in science. To see this, just consider a simple algorithm to produce an infinite series of numbers (like "X = X+1; reiterate"). Clearly, the output is infinite; but equally clearly there ain't much of interest that can be asked about the algorithm (yes, I'm aware of the psychological caveat that "interest" is a rather subjective matter, and yet you'd be amazed how relatively easy it is to have scientists agree on what are the really interesting questions about nature).

A second argument put forth by my colleague was that, "you never know, new questions may come up." The "you never know" argument against skepticism is perhaps the most popular one, and it is often considered to be either a clincher, or at least to clearly show that the skeptic is in fact close-minded for not even considering the possibility that he is wrong (indeed, my colleague followed through by asking me whether I was absolutely sure of my position -- which of course borders on a logical fallacy, because at that point he was beginning to shift from discussing the question at hand to attacking the personality of his intellectual opponent). But of course there are plenty of things we know to be impossible (think of many mathematical theorems as setting definite limits to logical possibilities). More broadly, the point is often to evaluate the relative merits of two positions, which means that both sides have to come up with a reasonable argument. To dismiss the other's view just on the ground that something is "possible" (without further elaboration of how this might be the case) is a cheap intellectual shot (and one that has been elaborated upon to perfection by religious apologists).

In the end, it was clear that my colleague -- like so many non-scientists who really dislike skeptics -- was simply uncomfortable with the very idea of a limit. He preferred to think of science as an unbounded set of possibilities, with few or no constraints. Very much like someone who believes in the supernatural, or is sympathetic to pseudoscience. It's the infatuation with mystery for mystery's sake, the very thing that skeptics threaten at every turn, and the main reason we are so despised. But of course skepticism is no threat either to human creativity, or to what we can actually do in practice. My discussion with my biology colleague was purely academic, in the strict sense of the word: neither of us seriously expects science to "end" any time soon, certainly not during our life times. And one can hardly make the argument that just because there are limits one's imagination becomes too constrained (on the contrary, imagination yields the best results when it does work within some rules: compare a movie whose story is internally consistent with one made of random sequences, completely unconnected to each other).

Reason and skepticism are not enemies of imagination and possibility. On the contrary, they are our most invaluable allies to make sense of the world.