In other cases, metaphor may be used to try to understand or condemn racism—or, less comfortably, to borrow for white protagonists the experiences of the marginalized. The X-Men are perhaps the iconic example here, with the oppressed, heroic mutants standing in for oppressed groups like African-Americans. Much more thoughtful is Philip K. Dick's Do Androids Dream of Electric Sheep?, in which differences between human/android (or, by metaphor, whites/non-whites) are presented less as absolutes than as profiling tools for law enforcement.

The second way in which sci-fi has handled issues of race is through tokenism. Non-white actors or characters are included, but there is no comment or discussion of racial issues. I presume that this is how the new Star Wars film will handle Nyong'o's presence, just as it was the way in which the original series handled Billy Dee Williams as Lando Calrissian.

It can be heartening to think about a future in which racial difference is no longer the weight it is now, as in Gene Roddenberry's Star Trek. But tokenism's refusal to directly confront racism can also end up backfiring. The white guy in the original Star Trek leads the diverse crew with the black woman as the space secretary, or the black best friend stands off to the side somewhere, as with Christina in the recently released Divergent.

A third approach is diversity. Instead of one or two white characters, a diverse setting imagines a world in which whiteness is not the default. Novelist Ursula K. Le Guin does this a number of times. In her Earthsea books, the main character, Ged, is red-brown. In Left Hand of Darkness, the main character, Genly Ai, is black, and the androgynous inhabitants of Gethen are, Le Guin says, "Inuit (or Tibetan) brown." As Le Guin herself notes, she was "wily about [the] color scheme," making it part of background detail rather than a central focus. This fact perhaps enabled the whitewashing of Earthsea for the television adaptation: Since the non-whiteness was done subtly, the adaptors felt justified in ignoring it. Still, the fact that they wanted to ignore it, and the fact that Hollywood virtually never imagines a future with a substantially different color mix than the contemporary U.S., is a sign of just how much Le Guin was pushing against the racial preconceptions of mainstream sci fi back in the 1960s and 1970s—and, for that matter, against the racial preconceptions of mainstream sci fi today.

Finally, the last approach is a direct one, in which racial issues in a sci-fi setting are dealt with as if they are continuous with, or affected by, racial issues in the present and the past. For example, in The Hunger Games, District 11, the home of Rue and Thresh, is presented as a segregated black city or region, subject to familiar prejudices and inequities—it's the poorest region, and its inhabitants experience especially vicious policing and persecution. Octavia Butler's Dawn is more subtle. The protagonist, Lilith, is black and her race inflects her relationships with both alien invaders and the remnants of the survivors of earth. Even after the apocalypse, Butler suggests, race and racism aren't that easy to escape.