Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

For the same reason, a call for everyone to think more scientifically must not be confused with a call to hand decision-making over to scientists. Many scientists are naïfs when it comes to policy and law, and cook up nonstarters like world government, mandatory licensing of parents, and escaping a befouled Earth by colonizing other planets. It doesn’t matter, because we’re not talking about which priesthood should be granted power; we’re talking about how collective decisions can be made more wisely.

A respect for scientific thinking is, adamantly, not the belief that all current scientific hypotheses are true. Most new ones are not. The lifeblood of science is the cycle of conjecture and refutation: proposing a hypothesis and then seeing whether it survives attempts to falsify it. This point escapes many critics of science, who point to some discredited hypothesis as proof that science cannot be trusted, like a rabbi from my childhood who rebutted the theory of evolution as follows: “Scientists think the world is four billion years old. They used to think the world was eight billion years old. If they can be off by four billion years once, they can be off by four billion years again.” The fallacy (putting aside the apocryphal history) is a failure to recognize that what science allows is an increasing confidence in a hypothesis as the evidence accumulates, not a claim to infallibility on the first try. Indeed, this kind of argument refutes itself, since the arguers must themselves appeal to the truth of current scientific claims to cast doubt on the earlier ones. The same is true of the common argument that the claims of science are untrustworthy because the scientists of some earlier period were motivated by the prejudices and chauvinisms of the day. When they were, they were doing bad science, and it’s only the better science of later periods that allows us, today, to identify their errors.

One attempt to build a wall around science and make science pay for it uses a different argument: that science deals only with facts about physical stuff, so scientists are committing a logical error when they say anything about values or society or culture. As Wieseltier puts it, “It is not for science to say whether science belongs in morality and politics and art. Those are philosophical matters, and science is not philosophy.” But it is this argument that commits a logical error, by confusing propositions with academic disciplines. It’s certainly true that an empirical proposition is not the same as a logical one, and both must be distinguished from normative or moral claims. But that does not mean that scientists are under a gag order forbidding them to discuss conceptual and moral issues, any more than philosophers must keep their mouths shut about the physical world.

Science is not a list of empirical facts. Scientists are immersed in the ethereal medium of information, including the truths of mathematics, the logic of their theories, and the values that guide their enterprise. Nor, for its part, has philosophy ever confined itself to a ghostly realm of pure ideas that float free of the physical universe. The Enlightenment philosophers in particular interwove their conceptual arguments with hypotheses about perception, cognition, emotion, and sociality. (Hume’s analysis of the nature of causality, to take just one example, took off from his insights about the psychology of causality, and Kant was, among other things, a prescient cognitive psychologist.)¹⁶ Today most philosophers (at least in the analytic or Anglo-American tradition) subscribe to naturalism, the position that “reality is exhausted by nature, containing nothing ‘supernatural,’ and that the scientific method should be used to investigate all areas of reality, including the ‘human spirit.’”¹⁷ Science, in the modern conception, is of a piece with philosophy and with reason itself.

What, then, distinguishes science from other exercises of reason? It certainly isn’t “the scientific method,” a term that is taught to schoolchildren but that never passes the lips of a scientist. Scientists use whichever methods help them understand the world: drudgelike tabulation of data, experimental derring-do, flights of theoretical fancy, elegant mathematical modeling, kludgy computer simulation, sweeping verbal narrative.¹⁸ All the methods are pressed into the service of two ideals, and it is these ideals that advocates of science want to export to the rest of intellectual life.