Time has jumped on the idea. But look a bit down in the article, and you might notice:

Still, it's not clear if spanking causes lower cognitive ability or if lower cognitive ability might somehow lead to more spanking. It's quite possible that kids with poor reasoning skills misbehave more often and therefore elicit harsher punishment. "It could be that lower IQ causes parents to get exasperated and hit more," Straus says, although he notes that a recent Duke University study of low-income families found that toddlers' low mental ability did not predict an increase in spanking. (The study did find, however, that kids who were spanked at age 1 displayed more aggressive behavior by age 2, and scored lower on cognitive development tests by age 3.)

Are we looking at parental IQ, here? Doesn't sound like it. People don't have the same IQ over their lifespan: it's possible that parents of lower IQ tend to discipline more often, and children of such parents also tend, whatever their childhood IQ, to have lower IQ scores as adults.

The last sentence also seems to beg the question: Is the kid becoming aggressive by age 2 because he or she is being spanked, or are kids who are aggressive at age 2 also more aggressive at age 1, and thus more likely to be spanked? That would seem like a rather large unaddressed question.

And, of course, there are other factors to be concerned about than IQ: would you rather have a smart child or a good one? Many of the world's most evil people were quite intelligent (Nazi scientists, for example, were brilliant) — but what they lacked what any sense of moral boundaries. Even if we accept the hypothesis (which not yet been demonstrated), that by no means settles the question if other long term effects aren't also considered.

Another little, tiny problem:

One problem with Straus' data is that some of the parents who tended to spank may also have been engaging in actual physical abuse of their children.

Really? Well, that just might be an important detail to keep straight. If not, what Straus has done is a bit like trying to study the effects of alcohol use without distinguishing between chronic alcoholics and adults who sip an occasional glass of red wine.

Here's another huge logical leap, passed off as sensible:

The preponderance of evidence points away from corporal punishment... Straus found that countries with higher GDP tended to be those where corporal punishment was used less often.

This is the basis for the claim that "whole nations" are affected by spanking? On the assumption that correlation must always indicate causation? It certainly couldn't be true that wealthy people tend to discipline less. (Nobody's ever heard of the "spoiled rich kid", certainly!) So it must be that a lack of discipline causes wealth!

So while we're at it: it's also true that countries which have the lower number of children are those with the highest GDP. So, of course, we'd conclude that the best way to boost the economy is not to have children. And since luxury cars tend to be found most often among the wealthy, it proves the the best way to acquire wealth is to go out and buy the most expensive car you can find.

This passes for science? How stupid can we get?

Answer: Fairly, apparently, when needing to prove a foregone conclusion.

Full disclosure: Although I'm not a parent, I know a number of kids who are almost never spanked or reprimanded. No matter how brutal their actions, their parents only talk, calmly, to them. They are, without exception, terrors. And even if you're only concerned about the kid's well being: they're also fairly unhappy kids. So while I don't claim to know which methods of discipline work best, I have rather strong reason to think some is absolutely necessary.

My gut feeling? Advocates of infinite child self-esteem will certainly treat this as a proven fact (indeed, if it's proven now, then on what basis were they asserting it for the last twenty years?) but the science will probably not bear this conclusion out over time. Usually, the important details arrive long have the headlines have gone. (Anyone remember the self-esteem movement, which is now, decades later, finally being discredited — too late for many of its victims?) But we'll see.