Science fiction and fantasy can do things that other genres cannot. I've talked about it before in posts such as this one. Today I'd like to talk about what SFF can do with theme.
I've always been skeptical of theme. I think "message fiction" is very hard to do well, especially in the written word. Television shows like Boy Meets World do it justice, I think, but few stories have been able to work such subtleties into an engaging narrative, Aesop's fables and parables aside. I like general themes that don't wish to answer a question. Think "Good vs. Evil" and "Identity." These sorts of themes have little to no "call to action." They only wish to broaden your perception of something, to make your question your thinking.
In his novella The Emperor's Soul, Brandon Sanderson deals with the concept of race; however, rather than dealing with the issue in real-life terms, he evaluates the theme from an exterior position. There is no direct parallel between the racism faced by the protagonist Shai and racism in the real world. Sure, it is similar in places, but there is a blend of multiple issues regarding race relations that could not be addressed in a story not set in a world removed from our own.
Is it wrong to exterminate an entire sentient species just because that species is trying to kill your own? This is the philosophical question asked by Orson Scott Card's Ender's Game and its sequels, especially Speaker for the Dead. Only SFF stories can delve into this sort of question. As far as we know, there aren't any of sentient species in existence, so any story possessing such creatures would automatically be fantasy or science fiction (or horror, I suppose, though it would be a blend with SFF).
Susan Palwick's novelette "Hhasalin" from the September/October 2013 issue of The Magazine of Fantasy & Science Fiction combines these two themes in an interesting way. (I'm going to spoil the story for you, so if you'd like to read it first, I would recommend going no further. It's an excellent tale.) Unlike Ender's Game, this story is written from the POV of a member of the sentient species that was wiped out (though not completely, same as [spoiler alert] in Ender's Game). Lhosi is a shaper. Her race's planet has been invaded by humans. The shapers fought back valiantly, but the clever humans developed a virus to eliminate their ability to shape (that is, fashion objects out of shapestone using a magical technique). With their magic lost, the shapers were defeated. The humans had only meant to cripple the shapers, yet in the process they inadvertently caused great illness to the native race. Some of the shapers are immune. Most have died out. Their only consolations are that the virus left the shapers with an inkling of their abilities still intact and that some human families have been compassionate enough to take in orphaned shapers like Lhosi. Lhosi herself is not subjected to a vast amount of racism, but the racism that she does face—and the greater racism faced by her race as a whole—is distinct from racism experienced in our world. Even so, this racism is applicable to the theme of racism as it applies to our everyday lives. The destruction of the shaper race was not intended by the humans, at least not on paper. Some of the characters, especially the doctor character who pops in from time to time, are very sympathetic. This is a different take on the question asked by Ender's Game and an interesting one.
Many of these sorts of themes can be explored by science fiction and fantasy. There is no direct application for these themes in our lives; I don't think there needs to be. The beauty of these themes, for me, is that they simply allow us to think from a genuine, neutral perspective about important issues. Politics can be stripped in large part from these themes, making them more easily digested by people of all walks of life. Other genres have a much harder time generating these perspectives.