Imagine a future society in which everything is perfectly logical. What could go wrong?

“Scientism” is the belief that all we need to solve the world’s problems is – you guessed it – science. People sometimes use the phrase “rational thinking”, but it amounts to the same thing. If only people would drop religion and all their other prejudices, we could use logic to fix everything.

Last week, US astrophysicist Neil deGrasse Tyson offered up the perfect example of scientism when he proposed the country of Rationalia, in which “all policy shall be based on the weight of evidence”.


Tyson is a very smart man, but this is not a smart idea. It is even, we might say, unreasonable and without sufficient evidence. Of course, imagining a society in which everyone behaves logically sounds appealing. But employing logic to consider the concept reveals that there could be no such thing.

There has always been a hope, especially as elites became less religious, that science would do more than simply provide a means for learning about the world around us. Science should also teach us how to live, pointing us towards the salvation that religion once promised. You can see this in any of the secular utopianisms of the 20th century, whether it’s the Third Reich, scientific Marxism, or the “modernisation thesis” of Western capitalism.

Yet each of these has since been summarily dismissed, and usually for the same two reasons.

Flawed science

First, experts usually don’t know nearly as much as they think they do. They often get it wrong, thanks to their inherently irrational brains that – through overconfidence, bubbles of like-minded thinkers, or just wanting to believe their vision of the world can be true – mislead us and misinterpret information.

Rationality is subjective. All humans experience such biases; the real problem is when we forget that scientists and experts are human too, and approach evidence and reasoned deliberation with the same prior commitments and unspoken assumptions as anyone else. Scientists: they’re just like us.

And second, science has no business telling people how to live. It’s striking how easily we forget the evil that following “science” can do. So many times throughout history, humans have thought they were behaving in logical and rational ways, only to realise that such acts have yielded morally heinous policies that were only enacted because reasonable people were swayed by “evidence”.

Phrenology – the determination of someone’s character through the shape and size of their cranium – was cutting-edge science. (Unsurprisingly, the upper class had great head ratios.) Eugenics was science, as was social Darwinism and the worst justifications of the Soviet and Nazi regimes.

Scientific racism was data-driven too, and incredibly well-respected. Scientists in the 19th century felt quite justified in claiming that “the weight of evidence” supported African slavery, white supremacy and the concerted effort to limit the reproduction of the “lesser” races.

It wasn’t so long ago that psychiatrists considered homosexuality unhealthy and abhorrent. There is at least one prominent, eminently rational psychiatrist who hasn’t come around on transgenders. And many scientists decided that women were biologically incapable of the same kind of rationality you find in men, a scientific sexism reborn in contemporary evolutionary psychology.

Positive vibes

And yet, despite its abysmal track record, people continue to have extremely positive opinions of “science.” As a sociologist, I do a lot of fieldwork with creationist evangelicals, and I’m struck by how rarely any of them dislike “science” as such; they don’t like certain scientists, and they especially don’t like evolution, but “science” is always just fine.

And for those who more strongly identify with the idea of rational thinking, their commitment is immutable. Just ask the 25 million people who “fucking love science”.

Part of the problem here is that nobody really knows what science means. Most people define it as the exploration of the world we live in, which is a fair if simplistic description (and not much on which to base a nation). The academic definition is frequently debated, without any really clear headway. (It’s hard even to figure out how to define physics, chemistry and biology.)

What is rational?

Philosopher Susan Haack has argued that science is, at its most basic, just thinking rationally. This is as good a definition as any, even if it leads to another problem: what do we mean by the word rational?

My work with creationists shows how impossible it is for humans to behave rationally. We are always informed by our biases. For example, a careful analysis of creationists’ scientific knowledge shows that they know as much science as anyone else. It’s just that they deny scientific claims.

In my fieldwork at one creationist evangelical high school, I found students perfectly capable of correctly answering every question about evolution in a biology exam. They simply used phrases such as “scientists believe” in their answers so as not to betray their creationist bona fides. This is actually an extremely rational way for them to handle the discrepancy between their faith and mainstream science.

In fact, creationism has a lot more in common with scientism than people such as Tyson or Richard Dawkins would ever admit. Like Tyson, creationists begin with certain prior commitments (“evolution cannot be true”, for example, substitutes for “science cannot be wrong”) and build an impressively consistent argument upon them. Just about everyone is guilty of some form of “motivated reasoning”: we begin with certain priors, and then find a way to get the evidence to do what we want.

The past mistakes of science should make us sceptical that it could be used to build a utopia. But, the scientists might say, science is most important for its ability to self-correct. Psychiatry has come around on homosexuality, for example. This may be true, yet it presents the precise reason why attempting to act only accounting for the “weight of evidence” is so flawed.

The elusive truth

Science may give us data, but it doesn’t mean that data points to truth – it’s just what we currently understand as truth. So how we act on the data requires nuance and judgement. It’s philosophical, maybe religious, and certainly political.

Scientists can’t tell us if it’s right to kill a baby with a developmental disability, despite how well they might marshal evidence about the baby’s life prospects or her capacity to think or move on her own. There’s no easy answer on how we ought to weigh those things up, just like there’s no easy way to decide whether tradition is superior to efficiency or monogamy is better than lots of random sex.

Scientism refuses to see this. The myopia of scientism, its naive utopianism and simplistic faith, bears an uncanny resemblance to the religious dogmatisms that people such as Tyson and Dawkins denounce.

Back in February, some of my sociologist friends retweeted another Tyson quip: “In science, when human behavior enters the equation, things go nonlinear. That’s why Physics is easy and Sociology is hard.”

We sociologists appreciated the recognition, even if some of us resented needing a famous astrophysicist as our hype man. Yet it’s simply galling that a person who can recognise the difficulties of studying social life somehow doesn’t connect those same challenges to their philosophical and political implications. If simply studying sociology is complex, governing society with it is anything but simple.

Science is not straightforward – as Tyson himself admits. Our interpretation of it simply requires insights and wisdom well beyond what science can provide. To claim otherwise is simply irrational.

This article was first published by Slate