Slate’s very wise “Human Nature” columnist, Will Saletan, gave me the honor of thoroughly critiquing my “Safe, Legal and Early” essay.
He suggests that my proposal by itself is politically impractical because it’s too complicated and because,

“people won’t take the more-but-earlier-abortions deal. Yes, they prefer earlier abortions to later ones, as Waldman’s poll data show. But those data say nothing about a trade-off for more abortions. So earlier timing isn’t a substitute for reduction. It’s an add-on.”

He was referring to my RU-486 example. I had noted that widespread use of RU-486, which causes an early abortion, might lead to fewer late abortions and an increase in the overall number of abortions. Under “safe,legal, early,” that’s a good outcome; under “safe, legal, rare,” it’s not.
But in truth, RU-486 is an anomaly. In every other case, efforts to make abortions “early” are fully compatible with efforts to reduce unintended pregnancies (for instance, through better family planning or economic assistance for women who want to carry a baby to term). “Safe, legal, early” need not lead to more abortions.
In that sense, Will is right: you could combine my approach with the traditional centrist one to form, as he suggests, “safe, legal, early and rare.”
Problem solved!
But I do believe that whatever its political popularity now, focusing on timing — as the Europeans do — ultimately is a better approach for the simple reason that it actually comports with the way most people make the moral calculation. Insisting on “rare” as a goal accepts the purist pro-life argument that any abortion is equally tragic. But most people do not believe that expelling a zygote in the first week* is horrendous. So remind me: politically speaking, why must those types of abortions be rare? Most voters would trade a myriad zygote expulsions for a meaningful reduction in second or third trimester abortions.

Conversely, given the revulsion most people feel about “partial birth abortion” in most circumstances, having them be “rare” — instead of non-existent or virtually eliminated — is morally unsatisfying, too.
But that may be a nitpick, if, as Will suggests, an awareness of timing were to become part of an overall strategy to reduce the number of unintended pregnancies while keeping most abortion legal. If you achieved safe and legal and early and rare, you’d end up with fewer overall abortions and the knowledge that those that do occur will happen as early as possible – which is what most women want, for practical and moral reasons.

*Changed from “day one” to “first week”