Ever since the Nobel prize winner James D. Watson asserted six weeks ago that Africans have innately lower intelligence, fervid debates about race, genes and I.Q. have sprung up on the Web, in publications and in conference rooms. But in recent days, along with long-simmering arguments over evidence, have come others about whether the topic is even worth studying, or whether it can be discussed openly without spurring charges of racism. Its a subject that almost dare not speak its name, said Howard Husock of the Manhattan Institute, a conservative research group, as he introduced a debate Wednesday night between James R. Flynn, the author of a new book What Is Intelligence? (Cambridge University Press), and Charles Murray, a co-author of The Bell Curve, the controversial 1994 book about intelligence that set off a previous free-for-all on race, genes and I.Q. The risk of giving ammunition to racists or undercutting principles of equality hovers over such conversations like an uninvited dinner guest. That unwelcome visitor has been loitering at the online magazine Slate since last week, when it ran a three-part series arguing that hard science is showing that blacks I.Q. scores are lower than those of whites and whites scores are lower than those of Asians because of genetically based differences in intelligence. Appearing on a site with a liberal bent and written by its generally liberal science and technology columnist, William Saletan, the articles drew particular attention and particular scorn. William Saletan and the Editors of Slate Demonstrate That They Are Not Members of the Genetic Elite was the headline on the Web site of the economist Brad DeLong (delong.typepad.com). On his popular political Web site, talkingpointsmemo.com, Joshua Micah Marshall referred to it as Will Saletans nauseating foray into black genetic pseudo-science. Mr. Flynn and Richard Nisbett, two noted researchers on intelligence, also criticized the Slate series as grossly one-sided. Mr. Flynn said he was most persuaded by evidence that the environment causes I.Q. differences, but added that certainty on either side is misplaced given that the research is still in its infancy. On Wednesday, Mr. Saletan posted a fourth article labeled Regrets, confessing that he had not realized that J. Philippe Rushton, a researcher on whom he had heavily relied, is the president of an organization that has financed a segregationist group. He also amended his previous position, stating that it was too early to come to any firm conclusions about the causes of racial differences in intelligence. If I had to do it again, I would have been much more circumspect about judging the evidence, Mr. Saletan said in an interview. He later added that he should have written about inequality and left race completely out of it. Jacob Weisberg, the editor of Slate, said that since Mr. Saletan is a senior writer, his posts went up without anyone there reading them. Given the sensitivity of the subject, Wills commentary should have been carefully edited in advance of publication, and it wasnt, he wrote in an e-mail message. Mr. Weisberg said he was disturbed by the casual what if thought experiment and some of the sources Mr. Saletan cited. I wouldnt have stopped Will from writing on this subject, but I would have challenged him on these and other issues, he wrote. He added that a rejoinder by another Slate writer, Stephen Metcalf, was scheduled to be posted Monday. Mr. Saletan said he was completely unprepared for the voluminous and vehement reaction. I did not mean to start a wildfire. A subject as sensitive and complicated as this deserves to have a higher level of proof, he said, adding that he erred in treating it like any other topic. I dont agree that its best not to discuss it, he said, but you have to do it in a responsible way and always with a constructive purpose. Judging from his own experience, he said, the Internet is not a place where that can be done at the moment. Im a little disappointed in myself, he added. Linda S. Gottfredson, a sociologist at the University of Delaware, insists that Mr. Saletan has nothing to apologize for. Ms. Gottfredson, who along with Mr. Flynn had been participating in a separate monthlong online debate about intelligence sponsored by the libertarian Cato Institute, wrote that Mr. Saletan may be the first journalist to so directly acknowledge the scientific evidence supporting a genetic explanation for racial differences in I.Q. and to be allowed to publish his views.