By Paul Krugman

Quite a few bloggers are having fun with Senator Marco Rubio’s bobbing and weaving in response to a question from GQ magazine during a recent interview:
GQ: How old do you think the Earth is?

Marco Rubio: I’m not a scientist, man. I can tell you what recorded history says, I can tell you what the Bible says, but I think that’s a dispute amongst theologians and I think it has nothing to do with the gross domestic product or economic growth of the United States. I think the age of the universe has zero to do with how our economy is going to grow. … I think parents should be able to teach their kids what their faith says, what science says. Whether the Earth was created in seven days, or seven actual eras, I’m not sure we’ll ever be able to answer that. It’s one of the great mysteries.

As I like to say, the G.O.P. doesn’t just want to roll back the New Deal; it wants to roll back the Enlightenment. But here’s what you should realize: when Mr. Rubio said that the question of the Earth’s age “has zero to do with how our economy is going to grow,” he was dead wrong.

For one thing, science and technology education has a lot to do with our future productivity — and how are you going to have effective science education if schools have to give equal time to the views of fundamentalist Christians?

More broadly, the attitude that discounts any amount of evidence — and boy, do we have lots of evidence of the age of the planet! — if it conflicts with prejudices is not an attitude consistent with effective policy. If you’re going to ignore what geologists say because you don’t like its implications, what are the chances that you’ll take sensible advice on monetary and fiscal policy? After all, we’ve just seen how Republicans deal with research reports that undermine their faith in the magic of tax cuts: they try to suppress the reports.

I’m belatedly reading Chris Mooney’s “The Republican Brain”; if truth be told, I was afraid that the book would be too much red meat for my own predispositions, and wanted to keep my cool. But Mr. Mooney actually makes a very good point: the personality traits we associate with modern conservatism, above all a lack of openness, make the modern G.O.P. fundamentally hostile to the very idea of objective inquiry. If they want your opinion, they’ll tell you what it is; doubters of orthodoxy need not apply, and will in fact be persecuted.

So don’t laugh over Mr. Rubio’s young-Earth apologetics. If he, or anyone else from his party, wins in 2016, the joke will be on us.

How We Know the Earth Is Old

One thing that kind of tickles me about Mr. Rubio’s age-of-the-planet stuff is that it leads right to one of my favorite science stories — the founding of modern geology by James Hutton, part of the Scottish Enlightenment.

Mr. Hutton was, for a time, a farmer — and in that occupation, observing the process of erosion and the laying down of deposits of various materials, he realized that the landscape he saw around him could be explained by the same forces operating over immense periods of time, as long as you posited that there were other forces uplifting ancient sediments to form today’s geological features.

How could he know whether this theory was right? He made predictions; in particular, that in places you would find “angular uncomformities,” or striated bodies of sedimentary rocks from different eras that were tilted relative to each other. And, sure enough, he found them.

And once you accepted that the landscape we see was created by the same processes we see every day, you also had to accept the notion of a very ancient planet.

Why do I like this story so much? I think because it’s science of a kind everyone should be able to understand; it doesn’t rely on exotic instruments or hard math (not that there’s anything wrong with either of these), just on keen observation and an open mind.

Too bad that such open minds are so rare in America today, at least on one side of the spectrum.