There is actually yet another sub-genre of fantasy that can help illustrate the point: urban fantasy.

Magical realism involves magic in the real world. Basically, in a magical realism story the world as a whole typically remains unaware of magic at the end. The magic either interupts normal people's daily lives (making it difficult for this genre to bring a fantasy element in particularly close to the beginning as some other have done) or it is part of a hidden sub-culture such as witches.

Urban fantasy, by contrast, takes the real world and essentially creates a parallel of it in which magic is commonplace or at least known.

Both of these are usually set in modern times, but magical realism can be set in a real past. (Or one the author thinks is real even though they're confused about what life was really like back then. )

When Urban fantasy is taken back in time, it is usually called alternative history.

Soft scifi doesn't. That's the line. Granted, it is a little fuzzy. How much explanation does someone have to give to make it hard? How much detail? It's a gut feeling, really.

Now, speaking VERY generally, soft scifi tends to focus on human reaction to whatever we're speculating about (the future, a new tecdhnology, alien exploration, etc.) but hard scifi can do that too. The only real difference is, as I said, the level of technical detail.

Hard scifi is not limited to future technologies, either. Some stories about aliens have more detail about the alien biology than others. This will be hard.

There is a scale, but I can tell you for certain that Card writes soft scifi. Asimov is a shade of gray, I'm afraid. He tends to write in terms of the human factor, but he also tries to use the scientific principles he understood at the time. I'd call him pretty hard. He's not like Clarke, though, who is the quintesential hard scifi writer.

I haven't read enough Philip K. Dick to make that call.

P.S. I hope I didn't derail any chance of getting the slipstream question answered.

There are several mainstream writers who have dabbled at one time or another in writing what they believe to be "science fiction" and most of it doesn't do a lot for people who are used to reading science fiction. (Examples include THE CHILDREN OF MEN by P.D. James--which spends the first several chapters on set-up, something science fiction readers usually don't need that much of--and ANCIENT EVENINGS--I think that's right--by Norman Mailer.)

Another way to distinguish between hard and soft science fiction is to say that hard science fiction is about the hard sciences (physics, chemistry, math, engineering, etc) and soft science fiction is about the soft sciences (psychology, sociology, anthropology, etc).

quote:

---

First Published in Asimov's Science Fiction Magazine, December, 2003.

It was in July, 1989 that Bruce Sterling coined the term in his Cat Scan column in the late great zine, SF Eye. Here's the big moment: "It is a contemporary kind of writing which has set its face against consensus reality. It is a fantastic, surreal sometimes, speculative on occasion, but not rigorously so. It does not aim to provoke a "sense of wonder" or to systematically extrapolate in the manner of classic science fiction. Instead, this is a kind of writing that simply makes you feel very strange; the way that living in the late twentieth century makes you feel, if you are a person of a certain sensibility. We could call this kind of fiction Novels of Postmodern Sensibility, but that looks pretty bad on a category rack, and requires an acronym besides; so for the sake of convenience and argument, we will call these books "slipstream." While I think Bruce's provisional definition holds up pretty well, most of his inductees into the slipstream club were folks whom we in the genre might actually think of as mainstream, for instance Kathy Acker, Isabel Allende, Martin Amis, Margaret Atwood, and Paul Auster. And those were just Bruce's "A's!"

---

I count Clancy as a hard SF writer, though he doesn't always write SF, his breakout novel was clearly near future SF, and several of his books have gone even further into the genre.

...a kind of catch-all term
proposed by Bruce Sterling in
1989. It's "slipstream" be-
cause it's not mainstream, but
slips through the cracks in
"normal" SF and Fantasy
categories.
...gives a familiar, ordinary...
world in which nevertheless
very strange things happen.

Had to post to this, just because I stayed up so late last night and fell onto it quite by accident.
--Raymond John