EAST LANSING, Mich. -- Robert Root-Bernstein is the first to admit it: He likes to find faults. When all those around him are nodding their heads, his instinct is to say, "But wait a minute . . ."
Mr. Root-Bernstein's training as a scientist compels him to take a theory, kick it around in his mind, test other possibilities and then explain why things may not gel.
Lately, the Michigan State University professor has been doing just that, kicking around the almost universally accepted premise that HIV, the human immunodeficiency virus, is the single cause of acquired immune deficiency syndrome or AIDS.
Most other heads are nodding. But for Mr. Root-Bernstein, it doesn't gel.
"The more I looked into the HIV theory, the more I kept finding holes," he said.
The professor thinks that HIV may be a relatively peaceful virus -- necessary, but not sufficient, to trigger AIDS. The way he sees it, HIV needs a crucial assist, probably from one or more other infections, dubbed co-factors.
Mr. Root-Bernstein's beliefs -- detailed in a book, "Rethinking AIDS," scheduled for publication by a division of MacMillan later this year -- are rejected strongly by nearly all AIDS specialists and public health officials.
"HIV causes AIDS. There's no serious question about that," said Dr. Peter Drotman of the Centers for Disease Control. Co-factor theories "have precious little evidence to support them," he said.
But there's enough evidence, at least to some eyes, for scientists such as Mr. Root-Bernstein and Luc Montagnier, the French virologist heralded for discovering HIV in 1983, to keep saying, "Wait a minute. . . ."
Mr. Montagnier, in June 1990, claimed a second discovery that hasn't gotten a hundredth of the attention of his HIV find. He declared that HIV needs help to cause AIDS, from a co-factor he identified as a mycoplasma -- a tiny bacterium.
Mr. Root-Bernstein believes he understands how some in the medical research establishment can reject such findings, given the years and billions of dollars invested in the premise that HIV is an inevitable line to AIDS.
"The problem is that we have people committed completely to HIV research," he said. "They have put, in many cases, more than a decade's worth of their lives into HIV only. To have that pulled out from under them is more than they can stand."
Mr. Root-Bernstein, who has given speeches to scientists and doctors around the country in the past year, has been riddled with an arsenal of adjectives -- stubborn, reckless, contentious, naive, stupid. He has even been called a liar.
"That's when I start losing my cool," said Mr. Root-Bernstein. "I'm not getting up and saying, 'I'm right!' I'm getting up and saying, 'Let's look at these things.' The most important thing is to get at the heart of the matter."
In 1981, at age 27, Mr. Root-Bernstein won one of the MacArthur Foundation's "genius grants," a no-strings pile of money to do research or write without worry of financial backing. From 1981 to 1984, he studied immune disorders in the California laboratory of Jonas Salk, inventor of the polio vaccine.
Now 38, Mr. Root-Bernstein teaches physiology at MSU. He said he was vexed by serious doubts about HIV in 1988 while planning an introductory lecture for MSU students about the causes of diseases.
The lecture would discuss four rules that German scientist Robert Koch formulated more than a century ago -- rules still taught to students of epidemiology today -- for proving that a specific agent causes a specific disease.
Mr. Root-Bernstein planned to apply those rules to HIV and AIDS. But the virus failed on at least two counts.
According to Koch, if a germ causes a disease, the germ must be found in every case of the disease. In a very small percentage of AIDS cases, no evidence of HIV is found.
Mr. Root-Bernstein said his research showed as many as 5 percent of AIDS cases in that group.
However, Dr. Celine Hanson of the CDC said the current percentage was below 1 percent and that in many cases where HIV wasn't found, the explanation was simple: There was no HIV test. Or a bad HIV test. Or an incorrect AIDS diagnosis.
Even so, Dr. Hanson admits that there is a very small number of befuddling cases in which a person appears to have AIDS but not HIV.
HIV also violates Koch's rule that the disease-causing agent, when injected into a healthy host, must produce sickness.
For obvious reasons, no one has injected HIV into a healthy human being. But the virus has been pumped into the bloodstreams of many species of animals, including monkeys, and the virus alone has not triggered anything in these animals resembling human AIDS.
One popular explanation is that certain diseases are specific to certain species and AIDS afflicts only humans.
Mr. Root-Bernstein doesn't buy it.
He said when he listens to scientists defend the HIV theory, he hears them making too many exceptions and allowances for the virus.