They're the antipodal pillars of the new men's fashion. JOSEPH ABBOUD designs for the corporate boss, while RONALDUS SHAMASK counts among his customers the Boss—Bruce Springsteen. But the uptown dandy and the downtown dude—both are based in New York City—share a credo of practicality and versatility. Both emphasize soft jackets constructed with only a light canvas foundation (or none at all) that look as smart with T-shirt and jeans as with a silk tie.

Like his onetime employer Ralph Lauren, Abboud, 39, relishes clothes that "look like they have character and heritage." That sentiment is shared by swells like Today's Bryant Gumbel, whose Abboud wardrobe often upstages that of even his clotheshorse co-host. But this Boston-born designer of Lebanese descent is not content simply to rehash history. "I redevelop the past for the future," he says. "Men have lived in very narrow confines. In the next decade, they'll see a huge change in what 'traditional' means." Abboud's definition melds American ease and European flair: broad, sloping shoulders; full pleated pants; nonvented jackets; earthy colors; and unexpected fabric mixes, such as a linen shirt with a suede vest. Says Marshall Field chairman Philip Miller: "Joseph Abboud has updated the establishment look for the modern establishment."

Shamask, 44, has, meanwhile, adorned clients from Jack Nicholson to Corbin Bernsen with a casual style he calls postclassic. His simple dramatic shapes and offbeat, usually solid colors (eggplant, anyone?) have marked him as a visionary. Yet the look is never bizarre. "I know as much about designers as the next guy who plays football, but I like Shamask's clothes because they're comfortable," says L.A. Raider defensive end Howie Long. Ideas come "from friends and people I see in the street," explains the Dutch-born designer, who has just started his own firm for the fall '90 season. "Clothes shouldn't look contrived," he sums up. "I love the power of simplicity."