Forty percent of Millennials think the government should be able to censor speech that's "offensive to minority groups," Pew reports. Older Americans are much less likely to be okay with that.

This is a stunning result in a country that prides itself on fighting bad speech with better speech, not with censorship. But perhaps it's not as surprising as it seems. For four decades now, the General Social Survey (GSS) has been asking a different but related question: whether "a person who believes that blacks are genetically inferior" should "be allowed" to "make a speech in your community." Consistently, about 40 percent of the general population has said no:

What may be increasing, however, is a zeal for censorship among the young specifically, at least when it comes to racially offensive speech. Historically, across a range of issues, Americans have tended to be strongest in their support for free speech in their youth. But that tendency doesn't show up in the Pew data, and here's what happened when I broke the above GSS question down by age and the decade of the interview:

Few would say that young people in the '70s were more racist than their elders, but they were still much more likely to say the speech should be allowed — the pattern we normally see with free-speech questions. That pattern has broken down over the years. This is partly the result of a rising Hispanic population (nonwhites are more likely to support the censorship of racist views), but that doesn't seem to be the whole explanation.

My first instinct was to blame PC universities, especially given recent events — but those without college are less likely to support free speech, both in the GSS and in Pew's survey. (According to a recent GSS study, this applies less to racist speech than it applies to other types of offensive speech, but it still applies.) When I looked at those age 23-32, roughly the decade after college for those who attend, I found declining support for letting a racist give a speech for all levels of education since the '70s.

An interesting complication: One study of 15 different GSS free-speech questions (including the one spotlighted above) claims that Americans are becoming more tolerant, largely because tolerance isn't fading out with age as much as it used to. But there's one group whose free-speech rights we're not tolerating more: racists. Judging by the charts above and Pew's findings, the young are playing a strong role in that. It's as if older people are holding on to their youthful civil libertarianism, while young people aren't developing it to begin with.

I wouldn't sign on to any theory yet. And again, support for censorship isn't new, even in the U.S. But something is going on with young people, and those dedicated to free speech should take note.

Thanks to Jason Willick of The American Interest; a Twitter conversation with him over the weekend prompted this post.

Robert VerBruggen is editor of RealClearPolicy. Twitter: @RAVerBruggen