THE CAUSE THAT FAILED: Communism in American Political Life by Guenter Lewy (Oxford University Press: $24.95; 359 pp.). Given the domino-like collapse of Communist governments the world over during the last couple of years, it's natural to wonder what once made Communism so threatening to many, and attractive to a few, in this country. The layman's curiosity won't be satisfied by this book, however, for Guenter Lewy, an emeritus professor of political science at the University of Massachusetts, is bent on beating a dying horse. "The Cause that Failed" is essentially a defense of anti-Communism from the Depression to the present, Lewy's argument resting on the infiltration by Communists of generally liberal institutions and movements like Progressivism, the NAACP, the ACLU, SANE, SDS and various others. Lewy's scholarship may well be impeccable, but his tone is more than a little irritating, and considering that he describes in some detail the almost laughable ineffectiveness of the Communist Party in the United States, it's odd that he felt the need to shoot his quarry with an elephant gun.