Will wants to maintain a distinction between doing research that kills human embryos that would be “discarded anyway” and creating embryos for research purposes. He writes, “The legislation [that Frist endorsed] would not allow funding for research on cells derived from embryos created for the purpose of harvesting cells. Nevertheless, many thoughtful people fear that the House-passed legislation puts the nation’s foot on a slippery slope leading to such a commodification of life.

“Life, however, is lived on a slippery slope: Taxation could become confiscation; police could become gestapos. But the benefits from taxation and police make us willing to wager that our judgment can stop slides down dangerous slopes.”

Some slopes are more slippery than others. There are several reasons to think that this one may be more slippery from the one leading from the creation of a police force to the creation of a gestapo. Creating embryos for the purpose of harvesting cells is not illegal in the U.S. Frist is not making his approval of the new funding contingent on its prohibition. Many of the therapeutic benefits claimed for the kind of research that Frist wants to fund are more likely to come from the kind of research that Frist and Will say they’re against. Many of the people who in 2001 were trying to make the same distinction Frist and Will are making have come out for cloning in the interim. And, finally, Frist’s argument that we need to fund embryo-destructive research because failing to do so will slow the advance of medicine is a rolling justification for each new abandonment of an ethical limit.