The debate over whether or not scientists, like doctors and many other professionals, should pledge adherence to a code of conduct continued this week in San Francisco at the annual meeting of the American Association for the Advancement of Science (AAAS).

"Rather than trying to promote conformity we want to promote the capacity to say 'no'," said Gerard Toulouse, director of research at the École Normale Supérieur in Paris. Toulouse urged for more "moral archaeology" into old oaths and their evolution to inform the debate.

The idea of an oath for scientists has gained strength in recent years as the pace of science has threatened to outstrip the speed at which its ethical implications are assimilated. But the idea is not a new one. Motivated by their horror at the role of science in the Second World War, the physicists Albert Einstein and John Kendrew championed the notion in the middle of the past century.

But many fear that such vows enshrine a conformity that is incompatible with the creative freedom central to scientific discovery.

Doctors vow not to abuse the power that they have over sick people. Scientists, Toulouse proposes should be examining the power they have over "our sick planet and making a formal commitment to its care". He points out that the shaping of modern medical oaths inspired by the 2,500-year-old Hippocratic oath shows that "it can be done".

But Toulouse cautions that an oath makes sense only as part of a university ethics curriculum that leaves students free to choose whether (and what) to pledge. Irving A. Lerch, outgoing president of the AAAS' Committee on Scientific Freedom and Responsibility agrees: "Young people training to be scientists need to receive a grounding in the humanities, to give them the kind of framework that will enable them to deal with these issues."

"History has shown that science and technology profoundly affects our values, but increasingly it must be shaped by those values" concurs Peter Blair, executive director of Sigma Xi, the US scientific research society. An enforceable pledge, Blair feels would engender the kind of "debate and revision of values and circumstance that could help scientists work responsibly within what he calls the "changing ethical landscape".

The Center for the Study of Ethics in the Professions (CSEP) at the Illinois Institute of Technology is doing some of the moral archaeology which Tolouse feels will be so instructive. They have collected, and made available online, an archive of more than 100 oaths from 22 countries and six continents.

"We want to see this issue being discussed in coffee rooms and committees," says Vivian Weil, director of the CSEP. "Something top-down is not the way to go," she says, believing individual institutions and societies are more likely to successfully institute codes of conduct than national governments. Indeed, about 15 oaths for scientists or engineers are currently proposed or in use.