RON Reagan, the new talk show host who happens to be the son of the former president, has an unnerving quality as a host. He starts off in neutral, almost lulling you, the audience, and his guests into thinking this is a genteel conversation.Everyone is relaxing in those beige chairs when about half way through "The Ron Reagan Show," the fire he has been quietly tossing paper on, then kindling, then logs, breaks out in a blaze of controversy. Rancorous guests and highly partisan audiences begin to mix it up, sometimes yelling, roaring, shouting, pummeling one another with words until it begins to look like the start of a street rumble. Ron Reagan stands elegantly by, a bemused expression on his face, as they go at it, almost seeming to be faintly surprised that his comments, questions, one-liners, and asides have turned up the heat. It doesn't matter whether his subject is steroids, "The New Black Wave" of directors, "Comedy is Serious Business,Gays, for Better or Worse," or "What's Wrong with Television." He carries it off. He's got charm and smarts. He does his homework but doesn't strut his ego around, drawing the guests and audience out, often to the point where they're ready to duel. Ron Reagan has had a career as a professional ballet dancer, of course, which doesn't hurt his timing and his stage presence; he likes to stand with his left foot on the stage, facing the guests or the audience like a lion tamer. But he also has begun to make a name for himself as a journalist, first from his stint as a correspondent parachuting into assignments on ABC's "Good Morning, America." He's written pieces for Newsweek, The Ladies' Home Journal, Interview, and Rolling Stone. A Yale dropout, he's verbally nimble. When a spokesperson for Nike bubbled on about what an idealistic, athletic company it was, he pointed out that they just sell shoes, are not in the business of athletics, and make huge profits using superstar bla ck athletes. He questioned how much of the profits go back into the black community. ON a show about "The Selling of Women," he made Cosmopolitan editor Helen Gurley Brown so comfortable she blurted out, "Women have always been supposed to be beautiful which was interrupted by wild laughter from an audience that had come to hear how to break the stereotype of a society that leans on women to be ever young and ever beautiful. Ron Reagan thrusts, jabs, parries, even needles a bit to get his sometimes contrary point across. Even on a show like the one on gays, where some of the panelists and audience were quite vicious to him personally (and about his 11-year marriage to Doria Palmieri), he kept his poise. He also books some good guests. On the comedy show (A. Whitney Brown, Harry Shearer, Will Durst, Merill Markoe, Steve Allen) when Ron Reagan asked, "Anybody troubled by the state of comedy today?" Steve Allen answered, "It's too dirty. Eight-year-old people can see filthy comedy on cable." Allen also tossed off one of the great lines: "Comedy is about tragedy." Most recently, the show has dealt with contemporary medicine and in perhaps the most explosive piece yet, with journalistic ethics. The Ron Reagan show, syndicated on 110 stations (usually at 11:30 p.m.), is a sure thing for 13 weeks.