He. When I was talking about "scientific basis" I was referring to what within the story could be explain with technobabble. I knew I should've made that clearer. :P It's like that Doctor Who episode where he explained the werewolves as entities whose change is triggered by the wavelength of the moonlight. It doesn't have to be based on current science, just to have that feeling and technicisms, created by the author or not.
Soft sci-fi is much less bound by the 'must have a scientific explanation' thing. As I understand it, the main difference between soft and hard sci-fi is that in the first, the technology is frame for the story, and in the second, the story is an excuse to explore the technology. Thus, the time spent explaining the details of how stuff works would mark the difference, wouldn't it? What do you think?
Personally I'm partial to the inverse of Clarke's third law. "Any sufficiently advanced magic is indistinguishable from technology." Yes, I agree that one is a great law too. I'm actually sorry I didn't mentioned, but it slipped my mind.
What I wanted to do (and I did it badly, by the looks of it ^^U) when I mentioned Clarke's third law was that it's always a good idea to establish the rules of our game at the beginning of the story --the first chapter in a novel or the first paragraphs in a short-story. Because if we change our minds midway and we make an unjustified twist, it's very possible that the reader will feel cheated. And it would talk badly about our skill as authors.