It’s easy to see that science is a valuable tool for understanding our world. Most modern technological advancements are based upon scientific knowledge—the computer upon which I type this column and the internet over which I communicate it would not be possible without science. What is harder to understand is how science actually works to obtain new knowledge.

Philosophers of science continue to debate just why science is so effective. So, I can sympathize with non-scientists who are often confused by its machinations. Non-scientists often talk about science “proving” something or finding “irrefutable evidence” for a theory, but the nature of scientific knowledge doesn’t allow for that kind of certainty. That’s why most scientists are reluctant to talk about “truth” and instead talk about “probably correct.” And yet, even with that kind of fundamental uncertainty, science is still the most valuable and effective tool we have for understanding the natural world.

One way to think about how science works is to consider it a weeding process. Science doesn’t prove a theory right so much as it disproves incorrect theories. There are a lot of ideas out there about how the world works; the scientific method is effective at weeding out those theories that are demonstrably wrong. What is left at the end of the day represents scientists’ best guesses as to how the world works. As Sherlock Holmes so aptly put his method: “when you have eliminated the impossible, whatever remains, however improbable, must be the truth[!]”

However, unlike Holmes, scientists realize that their methods don’t “prove” a truth, but instead simply measure available theories against the evidence. Whatever theory survives these tests isn’t necessarily the “truth”, it is just better than other currently available theories. Scientists have learned to live with this uncertainty—to surf, as it were, on the very limits of what can be known. It may seem an odd way of doing business, but it makes science a self-corrective enterprise—one that is constantly correcting, updating and elaborating upon what we know.

This is why scientific knowledge always seems to be a work in progress. There is always some chance that our current understanding is incomplete or that it can be improved upon. But this tentative nature of scientific knowledge is built into the nature of science. If you wonder how any process built on disproof could possibly work, you are not alone. Yet work, it obviously does.

Let’s take a concrete example: the link between smoking and cancer. As early as the 1930s, doctors recognized a correlation between cigarettes and lung cancer. But a correlation isn’t necessarily evidence of a cause—just because you can show a correlation between things doesn’t mean that there is a direct causal link. After all, as the tobacco industry at the time correctly pointed out, there could be other explanations. For instance, those who engage in smoking also tended to live in urban areas, or engaged in other unhealthy habits, such as drinking alcohol. Perhaps these other factors are really responsible.

Originally, there were numerous other possible explanations for the correlation between smoking and cancer. How then did scientists determine that the link between smoking and cancer was causal? They did studies that ruled out those other possible explanations. And, “when you have eliminated the impossible, whatever remains … .“ There is always the “possibility” that new evidence will bring to light an alternative mechanism for smoking and lung cancer, but that possibility becomes vanishingly small as we elucidate the physiological mechanism underlying the link between the two. So small, in fact, that if you take up smoking because my article convinced you that there is “no irrefutable proof of the link between cancer and smoking,” you are, by definition, a fool.

Often you’ll hear the misguided claim from science’s detractors that the scientific community is resistant to the evidence against their “pet” theories. But, because science thrives on disproof, this claim is nonsense. An individual scientist may cling to their own theory, but the scientific community is always skeptical; it wants theories tested. So, being a working scientist at the cutting edge of research means that one is always flirting with the possibility of being wrong — indeed, being wrong is an occupational hazard of doing science.

Readers can email the author at: jm.horner@yahoo.com

Laura Benjamin Photo by Laura Benjamin Communications