You might assume that science and the acceptance of science would advance together, in lockstep. That as our understanding of our bodies, and our planet, and our universe became more complete, it would be harder for skeptics to refute that increasingly detailed picture of the way things work. Looking around today, that’s clearly not the case.

In some instances, it’s hard to sort out whether the disbelief is genuine or cultivated for other reasons. Do oil executives really not think climate change is real? Or is their denial a pose–another business strategy to maximize profits for as long as possible? We can’t be sure. In many other cases, though, the reality is painfully clear: Some people just don’t trust science. But why?

Michael Hanlon, writing in Aeon Magazine, puts forward a few ideas. The first is simply that today’s science is too advanced:

One factor that is often ignored by champions of reason is that science is hard, and getting harder. In the mid-19th century, the ideas of British naturalists such as Charles Darwin and Alfred Russel Wallace took hold in part because they were so simple and intuitive (and in part because Darwin was such a clear writer). In those days, it was just about possible for an educated layman to get a grip on the cutting edges of science, medicine and technology. The same feat would be laughably impossible today. The intellectual giants of the 19th century were probably the last humans alive able to know just about everything important that could be known. Today, it is a challenge to know everything about even a tiny subset of knowledge. There are professional scientists who know nothing more than laypeople (and often rather less) about the world outside their own narrow disciplines. It is hard to become a molecular biologist, or a doctor, or an engineer. Yet it is relatively easy to grasp the ‘precautionary principle’ — the belief that, in the absence of scientific proof that something is harmless, we must assume that it is harmful. But, as Lewis Wolpert, professor of cell and developmental biology at University College London, has pointed out, this addled creed would have led early humanity to ban both fire and the wheel.

It might be a little too tidy of an explanation, but it rings true to an extent. I have no way of knowing, really, how vaccines or quantum mechanics work, but I trust that scientists do. I have faith in the scientific system. Others don’t. And, as Hanlon goes on to explain, there might be reason not to blindly trust science.

We must also accept that reason doesn’t always live up to its own standards. The motto of the Royal Society is Nullius in verba — ‘Take nobody’s word for it’. In reality, though, science is dominated (like any field) by the great and the good, grandees whose word is taken as read. The world of reason is itself riddled with feuds, egotism and, occasionally, downright fraud. Scientists and doctors are people, not machines. They are driven by the same forces that motivate professionals of any kind — which include money, sex, the desire to be respected, liked and even feared alongside the more noble impulses of curiosity, determination, professionalism and perfectionism. And so we must accept that corners can be cut, publications can be biased, and the peer-review system can be corrupted. To paraphrase Winston Churchill’s dictum on democracy, peer review is the worst system there is for evaluating scientific claims, except for all the others. Plenty of things look like science but are not; the American physicist and Nobel laureate Richard Feynman called this ‘cargo cult science’. Many of the psychological findings that make their way into the newspapers — together with ‘formulas’ for the perfect love-match, the perfect day, or the perfect sandwich — are no more scientific than angelic reiki. We must accept that science is not a well-maintained Swiss watch so much as a ramshackle, creaking machine held together with shims and bodges.

As Hanlon points out, science has always shared the stage with silliness to some degree–he reminds us that Sir Isaac Newton himself believed in alchemy–though Hanlon admits that the silliness may well be more rampant today. Vaccinations have saved millions of lives, but some people still decry them. Extreme weather is the new norm, but some still refuse to accept the reasons why.

But maybe that’s because smallpox and wildfires are too distant, too abstract for some when they only exist as stories on the news. Perhaps sometimes belief requires a certain degree of intimacy. As individual people inevitably come into contact with these things themselves–when a cutting-edge treatment saves their child from a life-threatening illness, or when their own house is wrecked by some unprecedented natural disaster–maybe then we’ll start to see them convert.

Read the full article over on Aeon’s website.