Originally Posted by
Throbert McGee Hmmm. To me, the term "soft science-fiction" in English often implies a "space opera" in which faster-than-light spaceships, time travel, telekinesis, and other very unlikely things are simply taken as real and scientifically explainable (i.e., non-magical), though without any attempt to explain how they actually work. Both Star Trek and Star Wars could be considered "soft" in this sense. But Star Trek, which frequently discussed 20th-century problems like racism and the Cold War in allegorical terms, could also be called "soft" in the "social" sense.
In contrast, Heinlein's The Moon Is a Harsh Mistress describes in believable and realistic terms the technical possibility of using a rail-gun catapult to launch cargo from the Earth to the Moon, without using "magical" techno-babble. For this reason the novel is often regarded as exemplifying "hard" science fiction. (Of course, Heinlein certainly gets some things quite wrong -- he assumes that photo-realistic CGI video doesn't get invented until around 2075, a time when the Moon already has several cities and a permanent population of 3 or 4 million humans!) On the other hand, to the extent that it discusses libertarian theory and male/female sex roles, TMiaHM is "soft social" sci-fi.
The en.wikipedia article about "soft science fiction", by the way, gives Orwell's 1984 as an example of "social" sci-fi, and Čapek's R.U.R. as a example of sci-fi that's "soft" in the sense that the robots might as well be magical golems.