Chris Mooney of Mother Jones recently reviewed Harry Collins’s book, Are We All Scientific Experts Now?, and argued that the public has “no business challenging scientific experts.” Collins’s early work was actually an attempt to debunk the 1950s unthinking reverence for scientific expertise. “Coming out of the 1950s heyday, [Collins] argues, scientists were treated as almost mythic luminaries and geniuses who couldn’t be questioned. And that just wasn’t accurate.”

But Collins’s recent book, the subject of Mooney’s article, combats the subsequent devaluation of expertise brought on by popular skepticism of the scientific community. The assumption of a radically postmodern attitude toward the authority of information caused many to assume that knowledge, like belief, is purely socially constructed. This presupposition undermines much of the scientific community’s rhetorical clout, in addition to muddying the public forum: if expertise cannot be trusted, what can be?

But, as a recent National Geographic article points out, the authority of science has often been misappropriated, with dangerous consequences. For instance, it has been relied upon by the judicial system to legitimate unjust rulings: in one particularly infamous case, Buck v. Bell, the court cited scientific evidence to prove that reproduction on Carrie Buck’s part would burden society with criminality and imbecility. She was forcibly sterilized. Justice Oliver Wendell Holmes Jr. famously wrote in the opinion, “three generations of imbeciles are enough.”

The National Geographic article explores the implications for the use of scientific data in contemporary court cases, pointing out that genetics research is being pointed to by defense attorneys with increasing frequency in order to mitigate their clients’ sentences. But the author also takes note of the limitations of scientific findings when they are applied to complex human situations far from the laboratory. She notes that after the Newtown shooting, the Connecticut Medical Examiner took the unusual step of commissioning a screening of 20-year-old Adam Lanza‘s DNA:

The screen will find something. Each of us carries genetic mutations somewhere along our 3-billion-letter DNA code. Some mutations are benign, some are not; some have huge effects, others tiny. But there’s no way to know how (or whether) any of them affects behavior.

Another thing I’d bet on: The media (and the public) will use the results of that genetic screen to explain what Lanza did. We all want answers, and a genetic test seemingly provides a long string of them. Answers from science, no less. But, as was pointed out by many scientists and commentators at the time, searching for answers in Lanza’s DNA is futile. “There is no one-to-one relationship between genetics and mental health or between mental health and violence,” read an editorial in Nature. “Something as simple as a DNA sequence cannot explain anything as complex as behaviour.”

That’s just it: science answers questions of how, not why. Insofar as the American code of law was written to uphold a set of moral goods—the sanctity of human life, property, and liberty among them—the judgments of the courts are not strictly rational, but moral as well.

Collins’s defense of scientific expertise is not totally flawed, but it is incomplete: the strict rationality of data fails to take into account the human being in its entirety. Mooney admits that the scientific community is flawed and “full of foibles, errors, confusions, and personalities,” but turns these complications against those who might challenge scientists’ credibility, arguing that only other scientists are familiar enough with the field judge its disputes.

When science is brought into the public discourse, however, it cannot help but be engaged by other modes of knowing. Methodological expertise does not protect the scientific community from human fallibility, and it certainly does not imbue their research findings with policy or ethical imperatives. The Court in Buck v. Bell failed to judge the science it was presented at the time by the moral and legal defenses of the person that could have prevented a black mark on American jurisprudence. The genes of Adam Lanza, however they are arranged, are insufficient to explain his last, horrific actions. The business of science is to investigate the world with reason; the business of law, to interpret and judge the world in the context of both reason and human passion.

Reason, as Dostoevsky said, “is an excellent thing, [...] but reason is nothing but reason and satisfies only the rational side of man’s nature, while will is a manifestation of the whole life, that is, of the whole human life including reason and all the impulses.”