Scientific literacy is usually measured through surveys that ask questions about basic scientific facts, such as, "Do the continents move? Does water boil at lower temperatures at higher altitudes? Are radio waves used to make cellphone calls? Did humans evolve from earlier life forms?"
In one survey of this kind, conducted in 2014 by the Pew Research Center, only 6 percent of a random sample of American adults correctly answered 12 such questions. A National Science Foundation study done around the same time found that only 74 percent of Americans knew that the earth revolves around the sun.
Ignorance is nothing to be proud of, but so what if many people fail these quizzes? The answers, if anyone needs them, are just a few pokes away on a smartphone. So why does it matter if Americans don't know this stuff?
One answer is that scientific literacy makes people better citizens of a democracy. Understanding science, even basic facts, helps voters distinguish between candidates with sensible policies for dealing with real problems, such as global warming, and hucksters who rouse support by exploiting fear and ignorance.
That's a pretty good answer. The less people know about what the world is made of and how it works, the more vulnerable they are to snake oil pitches of all kinds. The more people know, the more able they are to distinguish sense from nonsense and good policies from bad ones.
As a child of the post-Sputnik science boom of the 1960s, it seems odd to have to make these points today. But in the current political climate the need to make them is so pressing that thousands of scientists will gather in Washington, D.C., on April 22 to hold what is being called the March for Science.
The message of the march is that science is the best means we have for creating the knowledge needed to solve our nation's problems, and that to ignore or disparage science for short-term political or economic gain is foolish and self-defeating. The march aims not to politicize science but to protect science from being politicized in a damaging way.
Underscoring the value of science in general and the need to use science to inform policy making is certainly worthwhile. But what is also needed to solve the problem of people being misled into disparaging science is an explanation of how science works. It's good to know scientific facts, but it's even better to know how they're arrived at.
In a nutshell, what science does is to impose rules of inquiry that control the biases of perception and reasoning that would otherwise impede our ability to accurately know the world around us. This is part of what makes science such a powerful way of knowing. It's also what distinguishes science from common sense.
Common sense can work well enough to get us through the day, provided that one day is pretty much like the next. But common sense, albeit essential, is based on casual observation (the sun appears to revolve around a flat earth). We also tend in everyday life to see only that which affirms our existing beliefs. Science gets us out of this trap.
Science does this by exposing ideas to experience. "Experience" here refers to the results of careful, systematic observation. When ideas stand up to experience in crucial tests - when they are consistent with what is learned through painstaking measurement and observation - they are seen as worth keeping.
When ideas don't stand up to experience, when they conflict with the results of careful and repeated measurement and observation, those ideas are modified or discarded. The ideas that hold up over time, ideas that consistently align with the best available data, are crafted into theories that may come to be widely accepted in a scientific field.
Such acceptance is always provisional. In science, theories are not timeless dogma. They are subject to revision in light of new evidence.
By retaining ideas that appear to be true and discarding those that experience shows to be false, scientific knowledge grows in scope and accuracy. This is how science comes to deliver better results than even the smartest guesswork. The proof is all around us, embodied in the medical, transportation, manufacturing and communication technologies of the modern world.
It's also crucial to understand that science is a communal activity. Scientists learn from, challenge, try to replicate and build on each other's work. The communal aspect of science is what makes it self-correcting. If one scientist gets it wrong, someone else will eventually catch and correct the mistake. In the long run, wrong ideas wash out.
Finally, it's important to understand that in science no one study delivers the final truth. What matters is the weight of evidence. This is determined not only by the number of studies converging on a given finding but also by the quality of those studies.
People who don't understand the weight-of-evidence principle will often cherry pick studies to support a view that defies scientific consensus. This is often the case when non-scientists or people without relevant expertise claim scientific support for views - vaccines cause autism; evolution is in doubt; global warming is a myth - that were considered, tested and rejected long ago.
Of course science can't tell us everything we need to know as human beings. It can't tell us which values are best, or why compassion is better is than cruelty, or how to live a meaningful life. For this kind of knowledge we must turn elsewhere.
But when it comes to finding out, as accurately as possible, what the world is made of and how it works, nothing works better than science. Anyone who disparages science either doesn't understand how it works, or they understand only too well how to exploit ignorance for their own advantage.
