Health care is back on the political front burner. Not that anyone is talking about a major overhaul, like the ill-fated Clinton plan that banished the issue from polite political discourse for nearly six years. Instead, both George W. Bush and Al Gore are targeting isolated pieces of the health care system: prescription drug benefits for seniors, coverage for the uninsured, and a bill of rights for enrollees in managed care plans. This is the kind of incrementalism now blessed by conventional wisdom--a fix here, a fix there, and eventually it will all add up to universal, affordable coverage.