When we talk about science-fiction, we hold two different ideas in our heads. First, we think of lasers and space ships and so on. As I discussed previously, I don’t particularly see this to be science-fiction, but rather the clothing that science-fiction wears. Science-fiction should be about how new technology shapes the way we have to live our lives, not just wearing a sciencey setting. Here’s a quick litmus test for that. If the science suddenly became real, would we make such a movie in that era? That is, cars must have been science-fiction at some point. But would 2 Fast 2 Furious ever have been a sci-fi movie? Probably not. What is the distinction? 2 Fast 2 Furious doesn’t think about how the existence of cars changes human nature and society, it simply tells a story that uses cars. You could imagine the same movie with space ships, or horses, or any other speedy mode of travel. On the other hand, Minority Report is clearly science-fiction, being about the way we would react to some technology. Would we accept it? Would we fear it? Would we fight against it?
Bearing this in mind, Battlestar Galactica is one of the best science-fiction TV shows I’ve ever seen. Warning: there will be minor spoilers after the jump.
The entirety of the show is a reaction to the existence of cybernetic humans, and the distinction between human nature and robotic nature. There are other elements of the show that are not sci-fi, of course. There are interpersonal relationships, and there is the notion for fighting for the survival of the species. But these are only some of the central questions.
One of the central questions is ‘what is the difference between a cybernetic person and a flesh and blood person? BSG is definitely puling for ‘nothing, but those boundaries can be hard to overcome’. For example, several characters fall in love with cybernetic people (Cylons), and while their love is questioned by the remaining humans, and while the Cylons in question have to earn their trust over a long period of time, it is ultimately given where deserved.
As well, there is some question as to who is or isn’t a Cylon, both externally (who can I trust?) and externally (am I what I think I am?) that drives conflict. Finally, even among people who know they are Cylons, there is some question as to where their loyalties lie, with their personal history, or with their ‘species’.
Ultimately, the conflict is between ‘cylons’ and ‘people’, but is instead over how trust is built between cybernetic people and biological people, and how they can attempt to coexist despite vastly differing experiences.
All of these conflicts make BSG much more of a ‘soap opera’ style show. This has made many people question its sci-fi chops, probably because they think BSG should be lasers and stuff. But ultimately, science fiction is about exploring the hypotheticals of technology, not about ships and lasers, and BSG does that excess, despite any misgvings I may have about the show.
Fistful of Wits 
Hey Mattias, [dons copyeditor hat] I think you’ve omitted a few words!
[doffs hat] I appreciate the distinction you’re making though, and I agree with your central thesis — scifi must be ‘what if’; stories that could be told in any setting without any difference have a hard time claiming status as scifi. This may be a hard argument to maintain, however — does this mean StarWars is not scifi? What about StarTrek? Arguably, the utopian Federation is an impossible institution for a hyper-networked society in which any good can be produced immediately via synthesis or simulation. The StarTrek story frame is, in my opinion not scifi — as Gene Roddenberry put it, it’s ‘wagon train to the stars’. Individual episodes, however, sometimes qualify! (Others are more present day social commentary than they are an exploration of possible futures). If we use your thesis, Mattias, I think we must refer to many things currently dubbed scifi as science fantasy instead.
I think I agree, actually. I find it hard to consider Star Wars ‘sci-fi’, as it is a retelling of a number of traditional fantasy tropes (the old guide, the force that binds the universe, the father-son dichotomy, these are all traditional fantasy ideas) in a sci-fi setting.
I suppose I don’t want to say that they’re not science fiction, but instead that we should distinguish between setting and tropes, and that ultimately, ‘science fiction’ is an incomplete predicate, and that it requires a qualifier to be fully meaningful (in this case, setting vs tropes).
I am less familiar with Star Trek than most may expect, but I think it’s quite arguable that shows like Star Trek and Doctor Who are present day social commentary (wasn’t Doctor Who accused by the Thatcher administration of being anti-state propaganda, a claim they verified much later?), and I think also quite arguable that Star Trek is simply a Western in space (wagon train to the stars, as you mention).
On the other hand, my thesis will include certain types of historical fiction and steampunk as ‘sci-fi’, so perhaps the genre is not shrunk by my distinction, but simply…refined?