WASHINGTON — Matthew Gentzkow is the man who explained why the media are like ice cream. Gentzkow, who teaches at the University of Chicago, has just won the John Bates Clark Medal for an outstanding American economist under 40 (he's 38). He has some interesting ideas about the modern media, which he culled by studying traditional media. Namely, newspapers.
Along with economist Jesse Shapiro, also of Chicago, Gentzkow examined the ideological "slant" of newspapers by identifying various words and phrases favored by liberals or conservatives. For instance, conservatives often say "illegal aliens" when liberals prefer "undocumented workers." Another example: What liberals refer to as "the estate tax," conservatives call "the death tax." By tallying newspapers' use of liberal and conservative phrases, Gentzkow and Shapiro determined papers' political slant. This compromised their "objective" pursuit of the news.
But why are some papers more liberal and others more conservative? That's the crucial question.
Conventional wisdom holds that publishers impose their views on newsrooms. Not so, say Gentzkow and Shapiro. What actually happens is both more innocent and more insidious. Papers with more Republican readers tend to provide more conservative stories and language; papers in more liberal areas lean left in their coverage and story selection. (The study involved 1,000 phrases reviewed in 429 newspapers, representing about 70 percent of the nation's circulation. To gauge the politics of newspaper readers, ZIP code-level data on voting patterns and circulation were matched.)
This is how the media resemble ice cream, Gentzkow said in an interview. Just as ice cream makers give customers the flavors they want, newspapers give their readers the stories and slant they want. It's a market phenomenon. Ice cream makers strive to maximize ice cream consumption and profits. Papers try to maximize readership and profits. Newspapers are commercial enterprises that respond to economic signals and incentives. Editors, producers and reporters sense what appeals to their readers and try to satisfy these tastes.
Applied to cable news channels and the Internet, these same forces polarize politics. This is most apparent on cable, where MSNBC and Fox News have staked out liberal and conservative turf. Similar pressures affect the Internet: Conservatives favor the Drudge Report; liberals, the Huffington Post. By contrast, the shrinking mainstream media (newspapers, network television, newsmagazines) competed for more centrist audiences. Today, technology contributes to political polarization. To be fair, it's unclear how much this has happened. Gentzkow and Shapiro did another study to measure how much the digital media had abetted polarization. Not surprisingly, they found that cable and the Internet are more polarizing than the traditional mainstream media. But they also found that liberals and conservatives visit the other side's outlets frequently and aren't exposed to only one point of view. Also, many stories have no evident political slant.
Still, the larger message is that online identities are shaped by more than ideological competition. Commercial success depends on differentiating websites and cable channels from their rivals and attracting bigger audiences of true believers. Commercial imperatives dictate editorial decisions, in ways that are sometimes obvious and sometimes subtle. Cable news channels and websites feature stories and guests that please their core audiences and help to maximize viewers, unique page visits, or whatever.
Cable and the Internet have splintered media audiences and, thereby, created ferocious fights for ever-larger shares of ever-smaller fragments of the old mass market. The logic is powerful that the commercial imperatives of the new technologies will deepen the country's political divisions. People will stick to their familiar political flavors and disparage those who choose differently.
Robert J. Samuelson is a Washington Post columnist.