John Harwood’s Monday contributions to The New York Times’s “Caucus” blog provide a reliably level-headed take on the political news of the moment, often informed by political science. Today’s contribution—about how, for all the media sturm und drang about Barack Obama’s failure to sufficiently emote about the environmental catastrophe in the Gulf of Mexico, his public ratings have remained steady—is a good example. Here’s a key bit:

Presidential job approval is the most-watched statistic in American politics, a proxy for the chief executive’s power to persuade lawmakers, capacity to win re-election and ability to help or hurt in midterm elections.

It rarely moves rapidly. Because Americans know so much about presidents already, new information must be extraordinarily powerful to change impressions.

Harwood goes on to outline some plausible ways that the spill could, at the margins, make Obama’s political situation more daunting. But the point about the stability of public opinion in most contexts is key, and it’s something that should really hang on a placard above every pundit’s desk.

Political pundits should of course feel free—encouraged, even!—to disagree with whatever policy the administration is pursuing on a given issue. But they should be wary of making claims about the political risks of the president’s decision not to heed their demands that aren’t supported by the evidence.

In some cases, this sort of hackneyed argument is used to imply, without ever proving, that a pundit’s political agenda is broadly shared by the public—what Henry Farrell has dubbed “me the people” thinking. In the case of the oil spill, it’s not so much ideological disagreement as the press’s institutional need for novelty, drama, and volatility that drive the assumption that of course Obama is courting political risk by not playing the role the media expects. But the public does not face the some incentives—and, as Harwood notes, it’s apparently come to its own conclusions.

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Greg Marx is a CJR staff writer. Follow him on Twitter @gregamarx.