You might call it the cognitive divide — the split between an evidence-based worldview and one that is rooted in faith or ideology — and it is one of the most important fault lines in the United States today.

President Barack Obama called attention to the cognitive divide, and reminded us which side he comes down on, at the beginning of this week, when he chose the Princeton University economist Alan Krueger to lead his Council of Economic Advisers.

Krueger is a labor economist, and at first blush, that focus may seem the important part of his résumé. Unemployment, after all, is still above 9 percent, and the president has said job creation is his priority. But when you talk to the insiders about Krueger, what they emphasize is his mastery of data and his utter commitment to the truths it can be coaxed to tell.

Lawrence Summers, the former Treasury secretary and a Harvard economist, described Krueger, his former student, as a “total empiricist” and a “great data monger following the data where it went.” Lawrence Katz, a fellow Harvard economist and one of the pre-eminent labor economists, enthusiastically agreed: “Alan has an open mind and lets the data speak.”

Krueger’s passion for data runs so deep that one of his major professional projects has been, as Katz put it, “to actually improve the data.” Krueger was the founding director of Princeton’s Survey Research Center. When he can’t find the data he needs to answer a particular question, he goes out and gets it.