On Ask Metafilter, jenfullmoon asks “At what point do I stop watching the TV show Sliders?” General consensus seems to be to stop watching when the show strays beyond the one-off episodes from the first few seasons. I’m not going to argue that Sliders was a misunderstood wonderwork that was before its time, but I will defend the plot turn it takes in its later years, in principle.

The premise of Sliders was that Quinn Mallory invents a machine that lets him jump to alternate dimensions and see different versions of Earth, each usually based on a “what if” moment from history or culture. Each episode in the first few seasons would take one of these premises, explore it, and then send the characters on their way. As the second season drew to a close, the show did what I think every sci-fi show should do: expanded on its own premise. It went from “what if there were still dinosaurs?” to exploring the cast’s other-world doppelgangers to the question of if there might be other sliders from other worlds out there to, finally, the idea that sliding technology would be of military benefit. Granted, the show didn’t do much of this very well, and I don’t think the audience wanted these shifts in format, but if it has all been handled properly, and if the entire cast and writer’s room hadn’t been replaced several times, I think they would have had something there.

J.J. Abrams and Joss Whedon both did all of this years later to much more success (and I’d also say much greater failure given the expectations at play). Let’s look at a few of those shows and how their premises were played with over their runs. (Spoilers for Alias, Lost, and Dollhouse, and a very general summary of each season of The Wire.)

Alias started out as a spy vs. spy show. Syndey is a double agent, working for the bad guys and feeding information to the good guys to bring them down. They do lots of good spy stories and then, in season two, Syndey actually succeeds in bringing down SD-6 (in a rushed sort of way). The first season had this neat idea that the main characters thought they were good guys but really SD-6 was evil. That idea was executed perfectly in a Marshall-heavy plot where you see how proud he is of himself for his job. They could have kept this going, but there was no point – it wasn’t going to get any better than Marhsall calling his mom after a terrible ordeal and hearing how happy he was, but with us knowing that it was all a scam. So they just chucked that plot device and let us see all the characters deal with realizing they’d been duped but then let them right that by joining the real CIA. The show never pulled as good a swerve again (though I like the “Sydney goes missing for two years” season more than most), but I respect the Bad Robot crew’s willingness to mix things up.

Lost obviously didn’t hold itself together over the long run but had a similar “each season has its own thing” concept. Season one: the survivors are struggling to live day-to-day and there’s some other weird stuff going on in the background (polar bears, a hatch). Season two dispenses with the survivalist concept in providing the hatch and its supplies while setting up Locke and Ben Linus. Season three is about the Others. Later they get off the island, go to the past, and have a “what if” set of flash-sideways. All good ways to change up the constraints of the show, if not done satisfactorily.

Dollhouse started off with the idea that there’s a secret organization where you can rent customized humans, maybe for sex or maybe for espionage or whatever. Its second season introduced the idea that there was a darker past to the Dollhouse in the form of Alpha, a serial killer doll whose personality implants didn’t work properly. When it was cancelled the show hit the fast-forward button and ran through the rest of its season-long plots in one episode at a time in a wonderfully crazy manic way. It would have extended the premise beyond the idea that you can implant personalities into people as fantasies or for particular jobs to the idea that you could make dolls out of unsuspecting citizens, eventually developing into the idea of using the technology for military purposes: train a soldier instantly, convert your enemy’s troops to your own cause, program assassins, wipe the minds of entire populations. The finale jumps forward to a world that’s completely collapsed because everyone has been reprogrammed and no one can trust their own minds. Because the show was cancelled early this all happens very quickly, but watching it you can see how Whedon and Co. would have slowly built up each premise advancement so that it made sense based on the one that came before it.

The Wire was all about looking at how The System fails people. Season one showed the drug trade from a street-level perspective. Season two showed a larger view of how the drugs get into the country, how that ties in with other crime and organized labor. Season three showed why the police aren’t able to do much about it because of politics. Season four showed how schools fail kids and why they end up slinging drugs. Season five showed how the press is no longer able to be a watchdog for all that goes on. Because of the changing perspectives and ever-widening cast of characters, The Wire was able to very effectively communicate its points. It needed to move and change so that it could provide adequate perspective to make each argument.

The British TV industry famously isn’t built around the same need for longevity as ours. Shows don’t need to run for 100 episodes to grab the magic syndication cash cow. As such, the good British shows employ a much more “get in, get out” style of storytelling. HBO, Showtime, and AMC have adopted this more or less by establishing 12 or 13 episodes as their default season length. A shorter season reduces the need for a show to waste time on episodes that don’t advance the overall plot of the series. I think the shows above go even farther. Not only do they let the plot move at a good pace, they change the entire show up each season.

In conclusion, Lost and The Wire would not have been possible had Sliders not bravely reinvented longform serialized television by reinventing its premise with the Kromagg invasion of Earth and letting Jerry O’Connell cast his out of work brother in a leading role before leaving the show to marry Rebecca Romijn.