"Tolerance" gives me room to say, "I think you're wrong, but I'll defend your right to be wrong." "Pluralism" suggests, much more strongly than most folks admit, that there isn't such thing as right and wrong - and no such thing as truth and error. As it is practiced more and more in America, pluralism tends to require that you not only leave room for your neighbor to believe what he believes, but that you also refrain from disagreeing with it. There's a world of difference between the two perspectives. Tolerance promotes civility combined with clear thinking. Pluralism promotes civility combined with mushy-headedness.