Abe Polonsky, the blacklisted writer-director, makes the persuasive argument that since the informers didn't turn in names before the Committee put pressure on them, we (and in some cases they) can never know whether they acted from noble or ignoble motives. As he says of Kazan, "Kazan was not in the process of going around giving the names of people whom he thought were hostile to the society he had come to love. But the Committee faced him with a problem. Up to that point he didn't have a problem. All he had was a disagreement politically with some people. Since they were old friends they'd have had these arguments for years. I assume they did, you know. After all, Harold Clurman in The Fervent Years tells about the arguments they always had, and they disagreed with each other a hundred times.