Let's get controversial. Actually, let's get one thing straight first: It's not "red-baiting" when you're talking about a real-life communist. I'm not one for language taboos, especially concerning the history of our country. Sometimes it is what it is. Our memory of American politics in the middle third of the 20th Century is typically dominated by accounts of Hollywood blacklists, an out-of-control Senator Joseph McCarthy, and the cantankerous House Un-American Activities Committee. But the United States did have its share of actual communists in those days—people who would have preferred to see America go the way of Stalin. I...