WASHINGTON -- Scalding criticism directed by some conservatives at Sen. Bill Frist concerning his slightly revised position regarding federal funding of embryonic stem cell research is symptomatic of the casual cynicism that nowadays passes for political realism. Some ``social conservatives'' purporting to speak for ``values voters'' -- what voters do not intend their political choices to advance their values? -- insist, simultaneously, that Frist made a gross political blunder, and that he sacrificed principles to politics. This train wreck of logic makes one's head hurt.

     The president's firm policy -- he vows to veto House-passed legislation that would alter it -- is that the federal government will not fund research that involves the destruction of any embryo, so federal funding should support research only on the 78 stem cell lines that existed when he formulated his policy in August 2001. At that time Frist, who before then had proposed a moderately more permissive policy, accepted the president's policy.

     Now, however, Frist says that only 22 stem cell lines, of uncertain and declining quality, remain eligible for federal funding. So he endorses the House legislation that would expand federal funding of research. But it would encompass only cells from surplus embryos that have been created in vitro and frozen for couples who, having completed their fertility enhancement, donate them for research. These embryos would otherwise remain frozen or be destroyed.

     The legislation 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.

     It is carelessly said, and hence widely believed, that in 2001 President Bush halted ongoing stem cell research -- ``banned'' it -- thereby denying suffering Americans imminent medical marvels. Remember John Edwards' fantasy that ``when John Kerry is president, people like Christopher Reeve are going to walk, get up out of that wheelchair and walk again.''

     Beginning in 1996, under President Clinton, federal law said that no funds can be used for any research involving the destruction of a human embryo. And last week Frist noted that four years ago he said Congress should ``ban embryo creation for research'' and should provide funding for stem cell research only from embryos ``that would otherwise be discarded'' -- his position now.

     Americans' support of expanded research is a manifestation of national character. This nation was born at the sunny noontime of, and to a considerable extent because of, the Enlightenment. The essence of that historical epoch was, and an American characteristic is, vaulting confidence in the ability to apply science -- including what Alexander Hamilton in Federalist 9 called the improved ``science of politics'' -- for mankind's material and moral betterment.

     Some ``realists'' -- the sort who would have explained the Sermon on the Mount as a focus-group-driven exercise in political positioning -- suggest that Bush adopted his policy to pay for support he had received in 2000 from right-to-life conservatives. It does not seem to occur to such ``realists'' that Bush has the support of such conservatives because he believes in the policies he adopts. The realists' faux realism is the perverse reasoning that fuels government regulation of political campaigns: The fact that Group X supports Candidate Y explains -- causes -- Candidate Y's support for policies pleasing to Group X. 

     Such realists say Frist has now ``broken with'' the president because, having taken a number of stances pleasing to social conservatives who are disproportionately important in awarding Republican presidential nominations, it is time for him to tack toward ``the center.'' As though it is otherwise inexplicable why a physician would be receptive to a potential expansion of medicine's healing arsenal.

     The minor disagreement between Bush and Frist refutes the crackpot realism of those who cannot fathom the fact that people in public life often do what they do because they think it is right. Both Bush and Frist have thought seriously about this subject and come to mildly divergent conclusions. But neither conclusion crosses the scarlet line of supporting the creation of embryos to be mere sources of cells. And neither conclusion is the result of the sort of slapdash thinking that exaggerates the differences between them and explains those differences in terms of banal political calculations.