One of the neat things about science fiction is how easily it lends itself to examining our society in metaphor. One can use this technique to deal with controversial subjects with an elegance that sometimes eludes realism.
Take for example the Twilight Zone tale “The Monster Are Due on Maple Street”. (You can watch parts one, two and three here on Youtube.) This story, and you should watch the episode if you're not familiar with it, is a metaphor for the McCarthyite anticommunist scares that swept over the country in the late 1940s and early 1950s. This was a time when people were hauled off in front of congressional committees where they had to prove they were sufficiently patriotic in order to not be labeled a communist. The fear of being called a communist was so intense that people would often, to the pleasure of the House on Unamerican Activities Committee, name names of people, who would then be accused. And so the circle ran. It was an awful time in American history. People's careers, including my grandfather's and great uncles, were ruined because of these accusations. Senator McCarthy's fall came none too quickly.
Clearly Rod Serling was highly aware of this. He must have had great sympathy for the people who were unjustly hauled off and accused of being unpatriotic. “The Monsters Are Due on Maple Street” is a very clever allegory of this time. After a strange light flies overhead, the machines and electricity on Maple Street stop working. This causes general unease until a boy relates how these events closely follow the plots of alien invasions in his comic books. Then the unease coalesces into paranoia, and then one after another each neighbor is accused of being an alien. Every idiosyncrasy of each person is exposed to the light of this court of your peers and no person is above suspicion. The story ends with a tragic and sinister note, for after Maple Street descends into a riot, the camera pulls back and we see that two aliens actually have been the puppet masters of the entire scene, allowing humans in their paranoia, to destroy themselves.
Serling avoids any real partisanship here by avoiding the issue of communism entirely, making the paranoia the focus of the story. As the suspicion in the neighborhood increases, the watcher gets a sense of dread, knowing that unless something intervenes onto this simmering pot, it will end tragically. He's making a strong case for acceptance of each other's idiosyncrasies, for the alternative is horrible.
While allegory can be a very clunky thing, this story is a good example of how science fiction can use that technique and deal with a controversial topic. A realistic story of this nature might be accused of being partisan and unpatriotic (then and now), but by taking the paranoia out of its political context, Serling makes a strong point about what it means to be a neighbor. Alien invasion is still a pretty unrealistic thing, thank goodness, but that's the strength of the episode. By making the fear, the MacGuffin, something essentially ridiculous, we're free to see how the paranoia plays out without getting involved with the fear itself.