[Ilya Somin] Historians Against Trump and the role of experts in political debates

Historians Against Trump, a group of over 600 academic historians, recently posted an open letter urging voters to oppose the GOP nominee. The letter relies in significant part on their professional expertise and “the lessons of history,” as understood by “[h]istorians of different specialties” who have expert insight into “the ominous precedents for Donald J. Trump’s candidacy and the exceptional challenge it poses to civil society.” The group’s appeal to their disciplinary expertise has attracted the ire of critics such as postmodernist law and literature scholar Stanley Fish, who wrote a New York Times column attacking HAT:

By dressing up their obviously partisan views as “the lessons of history,” the signatories to the letter present themselves as the impersonal transmitters of a truth that just happens to flow through them. In fact they are merely people with history degrees, which means that they have read certain books, taken and taught certain courses and written scholarly essays, often on topics of interest only to other practitioners in the field.

While this disciplinary experience qualifies them to ask and answer discipline-specific questions, it does not qualify them to be our leaders and guides as we prepare to exercise our franchise in a general election. Academic expertise is not a qualification for delivering political wisdom.

I. Why Expertise Matters.

Contra Fish, experts often have good reason to suppose that they have greater insight into political issues than ordinary voters do. And, at least in many cases, the latter would do well to pay more heed to expert opinion, not less.

The idea that expertise is not a qualification for delivering wisdom would be immediately dismissed as laughable in almost any context other than politics. If you need to address a medical problem, a doctor’s opinion should count for more than that of a random sample of the general public. If your faucet is leaking, a plumber’s view on the subject is going to be a lot more valuable than mine.

Similarly, political controversies often involve complex policy issues on which experts on public policy have greater insight than laypeople. Not because they are generally smarter or more virtuous than the rest of us, but because that’s their field of expertise. This is especially likely to be a true in a world of widespread voter ignorance where most voters are “rationally ignorant” about policy issues, and often don’t even know very basic facts about government and public policy.

Historians are pretty obviously among the the experts who are likely to have useful insights on Trump’s candidacy. There are many historical precedents for Trump’s xenophobic program of massive restrictions on trade and immigration, targeting civilians, and weakening protections for freedom of speech.

Scholars who have studied that history will often have greater insight on Trump’s proposals than laypeople who have not. Not all the signers of the HAT letter have specialized expertise on historical issues relevant to assessing Trump’s campaign. But many do. Voters would do well to take advantage of that insight. Even the best experts aren’t always right. But, within their areas of expertise, they are more likely to be so than laypeople are.

II. What if the Experts are Biased?

Blind deference to expert opinion is a mistake. We should not defer to experts as much when they opine on issues that go beyond their professional competence, or when a seeming expert consensus is actually the result of ideological bias.

That’s why some of the most useful evidence of expert opinion comes from studies that control for the ideology and partisanship of the experts consulted. For example, Bryan Caplan finds that, after controlling for these and other variables, economists are