I was flipping through Eisenhower's Mandate for Change at random today, and came across this passage on page 331:
Supporters of McCarthyism represented it as simply a dramatic effort to awaken the public to the existence of some Communist penetration into all facets of our national life and to warn everyone of the need for universal alertness. Perhaps at its beginning the movement may have had some such usefulness. But almost immediately its methods defeated its purported objectives. Un-American activity cannot be prevented or routed out by employing un-American methods; to preserve freedom we must use the tools that freedom provides.