Science, Ideology, and the Myth of Exactitude

Most of us have heard that there are "exact" sciences, like physics and mathematics, and "soft" ones, like economics, psychology, or sociology. The first group, we're told, delivers solid truths that can be checked. The second is supposed to be a realm of opinion, where everyone is free to think whatever they like. The idea is so widespread that hardly anyone questions it. But it is wrong, and the mistake has real consequences: it leads us to believe that knowledge about society doesn't deserve our trust, and it leaves the door open to ignoring evidence whenever it's inconvenient. This essay explains why that divide doesn't hold up, and what distinction actually matters: the one between science and ideology.

Let's start with physics, the classic example of an exact science. Even physics isn't entirely exact. Every experiment has factors we can't control, and every measurement, however careful, carries a small margin of error. Modern physics has also discovered that, at the smallest scales, uncertainty is built into nature itself. When we call a result "exact," what we really mean is that it's such a good approximation that the error no longer matters. And it's such a good approximation because the phenomenon is relatively simple: we can identify almost everything that affects it.

An everyday example makes this clearer. If we drop a stone from the top of a tower, we can calculate quite precisely how long it will take to hit the ground, because only a few factors are at work, such as gravity and air resistance. Predicting whether the price of bread will rise next month is another matter entirely. Millions of decisions come into play: what farmers, truckers, governments, and shoppers do, the weather, even a war on another continent. Each of these factors is called a variable, and the difference between the sciences lies not in what they study but in how many variables are involved and how many of them we manage to understand. The social sciences aren't less scientific because they study people; they're harder because a society is an enormous system in which everything affects everything else.

More than two hundred years ago, the mathematician Laplace imagined that anyone who knew every factor behind a phenomenon could predict it with complete certainty. If we can't do that with society, it isn't because society follows different rules, but because for a long time we lacked the data and the computing power. That is changing. Today there are staggering amounts of information, and computers capable of analyzing it. Advertising and sales have already been through this: a few decades ago, nobody could say for sure what a given person would want to buy; today, thanks to data on what people search for and consume, companies anticipate our preferences with startling accuracy, even if they can't fully explain why we choose what we choose. Something similar is beginning to happen in economics. A good example is the 2026 Nobel Prize in Economics, awarded to Robert Hall and Michael Woodford for their work on how the decisions of individuals and firms explain the ups and downs of the economy as a whole, and how to stabilize it. Their work rests on theory, but also on data that can be checked.

And yet work like this is often brushed aside with a single line: "That's not an exact science." Put that way, it sounds like a profound criticism, but more often than not it's just an excuse. When the data contradict what someone already believed, it's easier to declare an entire discipline worthless than to honestly examine its arguments. Two very different claims need to be kept apart. One is saying "this particular study is weak," a legitimate criticism that can be argued with evidence. The other is saying "this science, as a whole, is useless," which can almost never be defended and which serves, above all, to end the conversation.

So how do we recognize a serious theory? The philosopher Karl Popper offered a very clear criterion: a theory is scientific when it sticks its neck out, that is, when it claims something the facts could prove wrong. Imagine an economist who says, "If the government takes this measure, prices will fall." If prices then rise, the theory has failed, and, paradoxically, that's a good sign: it means the theory could be tested. Now imagine another who says, "If prices rise, that's what I expected; and if they fall, that too." That theory can never fail, and that is precisely why it teaches us nothing: it explains everything and predicts nothing. Note that Popper's criterion judges theories, not entire disciplines. There are serious theories and vague ones in economics, in psychology, and in every other field. What separates them isn't the subject matter, but whether they accept being tested against the data.

The historian of science Thomas Kuhn offers another clue. He observed that when a science is mature, nearly all its researchers share the same basic ideas and methods. He called this underlying agreement a paradigm. While it lasts, nobody argues about the foundations and everyone gets on with solving concrete problems; that is why physics gives an impression of order and consensus. In economics or psychology, by contrast, rival schools of thought compete with one another, and this is often taken as a sign of low rigor. But Kuhn showed that physics went through that stage too: before Newton, those who studied light were split into camps that didn't even agree on the essentials. Disagreement, then, doesn't prove that a subject is less scientific; it indicates that the field hasn't yet found an explanation that convinces nearly everyone, which is harder to do when the system under study, like a society, has so many factors at play.

If neither the subject matter nor the existence of rival schools separates one science from another, where does the difference that matters lie? In the attitude each person takes toward their own ideas. An honest scientist knows the limits of what they know, puts their thinking to the test of the data, and is willing to change their mind when the facts demand it; if the evidence is weak, they say so. The ideologue does the opposite: they start from a conclusion they're already attached to and look for arguments to defend it, allowing nothing to contradict it. For them, ideas aren't tools that can be discarded; they're part of who they are. An ideology is, at bottom, a closed system of belief: it exists to defend itself, not to be tested. Science, done well, exists precisely to be tested, and to be abandoned if it turns out to be wrong.

This dividing line doesn't coincide with the one between disciplines. A physicist can cling to a favorite theory as stubbornly as others cling to a dogma. In the Soviet Union, for example, the government spent years imposing the ideas of an agronomist, Lysenko, that contradicted genetics, and those who questioned them were persecuted, with serious consequences for the country's agriculture. In Nazi Germany, some rejected Einstein's theory of relativity for political and racial reasons, not scientific ones. Rigor, moreover, isn't the same everywhere: it depends on the culture of each institution, on how research is funded, on whether findings are reviewed by independent experts, and on whether people are free to criticize. No subject, on its own, protects us from ideology.

History shows how far the damage can go when ideology overrides evidence. The Inquisition forced Galileo to recant what he had observed through his telescope and sent Giordano Bruno to the stake for his ideas, because they threatened a way of seeing the world that was meant to be defended, not examined. Nazism leaned on supposedly scientific theories about race that genetics flatly refutes, and it told people to stop asking whether they were true. In both cases, a system of belief closed itself off from correction, and the population was taught to value loyalty above truth. Authoritarian governments know this: a people who accept without asking are easier to control than one that demands proof.

That is why universities play such a valuable role. Their job isn't only to teach the young, but also to produce knowledge, test it, and protect the right to ask uncomfortable questions. They are, or should be, the place where any idea can be challenged. A university dominated by an ideology, whichever one it may be, keeps its name and its buildings but loses what matters most: the freedom to doubt.

Ultimately, what we need to defend is not a list of conclusions but a method: the habit of asking "What is the evidence?" and accepting that we might be wrong. That method is what allows us to correct our mistakes. A society that stops asking "Where is the proof?" and starts asking only "Which side are you on?" has lost its best defense against error. Protecting science, understood as an honest, open way of thinking that is always willing to revise itself, is one of the best ways we have of not repeating the darkest chapters of our history.

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