It's absolutely clear to me that the true predecessor of The West Wing, the great science-fiction show that ended its seven-season run this spring, is the movie Who Framed Roger Rabbit. The plot of the 1988 movie revolves around an attempt by the villainous Judge Doom (Christopher Lloyd, naturally) to pave over the enclave of ToonTown in 1947's Los Angeles to make way for a new system of "freeways." ToonTown is a protected zone where the animated "toons" who star in this era's movies live: the detective Eddie Valiant (Bob Hoskins) is hired to investigate a ToonTown-related murder and winds up—as one tends to—tied up while Doom explains his plans:

DOOM: Right here where we're standing, will be the cornerstone of my idea... the cloverleaf—an elegant cement structure that intertwines freeways.

VALIANT: What the hell's a freeway?

DOOM: A freeway, Mr. Valiant, is eight lanes of asphalt running uninterrupted from L.A. to Pasadena. Pasadena to Hollywood. Hollywood to Santa Monica. Someday everyone will be in cars driving happily, non-stop from one end of the L.A. Basin to another.

VALIANT: That's what this is all about? Tell me, who's gonna use your lousy freeway? We got the Red Cars, the best public transportation in the country.

DOOM: Not for long. We're retiring the Red Cars. People will drive, Mr. Valiant, because they'll have to. And when they drive, they'll have to buy our cars, our tires, our gasoline.

In the movie, Doom is defeated and Los Angeles is saved as a place with decent public transportation, an enclave for Toons and no freeways. The film tugs at the heart because it's a counterfactual: it posits a better place than the smog-choked, concreted-over, dislocated Los Angeles that we have now. Moreover, it says that by ending up with the Los Angeles we have, we've somehow failed to choose the right story—despite the obviously fantastic tropes it uses. For liberals in an era of an aggressively right-wing White House, The West Wing works the same way. It places an impeccably moral left-of-centre President at the heart of a web of hardworking, ferociously smart advisors; and it by and large allows them to find the complex problems of their world soluble.

The setup is simple to paraphrase. Episodes of The West Wing are set overwhelmingly in the White House; each 45-minute episode tends to throw a couple of stories—problems of government—into the air and resolve them by the end. (Howard Waldrop has a wonderful review of the first couple of seasons in which he argues that this set-up was a very close match for 1960s Star Trek, another series founded on irrepressible optimism about human nature.) The core cast for the first few seasons—President Jed Bartlet (Martin Sheen), his Chief of Staff Leo McGarry (John Spencer), his deputy Josh Lyman (Bradley Whitford), Press Secretary CJ Cregg (Allison Janney), Communications Director Toby Ziegler (Richard Schiff), and his deputy Sam Seaborn (Rob Lowe)—looks in hindsight like a dream team, a once-in-a-decade piece of casting genius. Most of those actors now have an Emmy or two—in Janney's case, half a dozen—to demonstrate the admiration of their peers. The premiere episode gave each of them a chance to shine in their most characteristic ways. Josh engineers the main action by hubristically telling the truth about fundamentalist Christians on television; Toby gets a few moments of fortissimo moral outrage at his stupidity; CJ corrals the press corps with a steely twinkle; Bartlet provides a bedrock of moral and intellectual authority; Leo, world-weary and politically astute, holds the whole show together. Rob Lowe, the notional star of the series, must have been taken aback to find himself just one member of a superb ensemble cast like this, and this was apparently behind his eventual departure a few years later. But for the moment, even Sam has a self-deprecating klutziness at odds with his movie-star looks.

Peak episodes of the series could vary from screwball comedy to the deadly serious. Late in the first season, for instance, came a glorious example of the former, "Celestial Navigation," in which another piece of Josh arrogance—the presumption that in CJ's absence he's capable of briefing the press—falls apart spectacularly. An obvious example of the latter is "17 People," from the second season, in which Toby figures out the President's most deeply buried secret: that he's had multiple sclerosis for some years and has concealed it from both his staff and the voters. One criticism of The West Wing is that problems are too often resolved by alpha males shouting at each other; "17 People" transcends that because of the intimacy of its setting—the crucial scenes are just between Toby, Leo, and Bartlet—and the scale of the stakes being played for. For my money, though, even more affecting is "Bartlet for America," from the point in Season 3 when some implications of the MS revelation are playing out. Leo is required to testify before Congress on the scope of his interrogation, and one of his interrogators is threatening to blackmail him with a public revelation of his past as an alcoholic. This is intercut with Bartlet's memories of Leo persuading him to run for President in the first place, a pitch sealed with a napkin on which Leo had scrawled "Bartlet for America." Spencer—himself a recovering alcoholic—gives an astounding performance, filled with dignity and, in the flashbacks, a potent sense of the fallibility he has been hiding. At the end of the episode, Bartlet hands Leo a Christmas gift: the original napkin, framed. This is one of Sorkin's favorite techniques: resolving the conflicts of the present by re-telling the stories of the past. (Bartlet's encyclopedic knowledge of the world—his Nobel Prize is just a sidebar on his CV—provides frequent opportunities for this, starting in the very first episode with a folksy story about a cut tomato revealing the face of the Virgin Mary.) So "Bartlet for America" is about redemption and possibility, and comes perilously close to sentimentality. It evades that, I think, through the performances and the sense that choosing a new path—for oneself, or for a country—is hard work.

In a sense, that's what I was referring to when I said at the start of this piece that I regard The West Wing as science fiction. On one level, of course, the claim is silly: there is nothing in the series outside the canon of current political or scientific possibility (or what we as outsiders might imagine those to be.) The West Wing is entirely mimetic. Of course, in another sense, it's trivially true that The West Wing is SF. It's a piece of alternate-world science fiction: presidential elections take place in 1998 and 2002, not in leap years; the September 11th terrorist atrocity does not take place; and global events in general follow a different track from our recent past. I want to argue, though, that it's SF in a more profound sense, the Roger Rabbit sense. It makes an argument, as SF does, about possibility, about what can be done, and it does so by presenting us with a world already showing a change from our own. (One might call this technique cognitive estrangement.) Science fiction has always, I think, been a peculiarly American genre because of its allegiance to a belief in possibility. Once this was geographical: a new frontier, somewhere out west, was always there to be discovered by anyone smart and brave enough. (And anyone who happened to be living there already might find themselves getting effaced from the story, like dumb aliens in a pulp magazine.) Sf moved this frontier out into space, the potentially infinite worlds out there to be discovered. But as the difficulties of space travel become more and more apparent, it might be better to say that SF's frontier is now temporal. It tells stories about what might be done with tomorrow, starting today. Lowe gets a speech making precisely these points in "Galileo," an episode about a failed Mars probe.

Whenever Bartlet has finished with some piece of business, he hollers "What's next?" at his secretary; this, I'm suggesting, is the same impulse that fuels our reading (and writing) of SF. It's the same impulse, too, that made Bill Clinton choose Fleetwood Mac's "Don't Stop Thinking About Tomorrow" for his inauguration, as well as his rhetorical tropes like the famous "bridge to the 21st century." On the same subject, here's Anthony Lane, in the New Yorker for 11th December, reviewing Neil Gabler's Walt Disney: The Triumph of the American Imagination:

To be gripped by a story, especially one that is trawled from the past, is everything [to Disney]. To realize that it might not be true, or that it might have been blown up out of all proportion, is no big deal. Changing its proportions, in fact, could be just the ticket, because what are fables if not stories that have been lofted out of the reach of regular experience, no longer scratchable by the quibbles of common sense?

You could make the same case about the fantastic in general, that it takes "realism" away from what stops it being exemplary, what stops it being as story-shaped as we'd like. (Disney's genius, says Gabler, was to have an instinctive understanding of the shape we want stories to be.) The problem, of course, is that the more exemplary a story becomes, the more difficult it becomes to believe in. Sorkin's solution was, for want of a better word, to aerate the story, and in particular the dialogue. The West Wing's plots are so dense with data, delivered at such exhilaratingly high speed (the kinetic direction can take a lot of credit here too), that it's all the unbriefed viewer can do to keep track of what's happening, let alone to start questioning how plausible it is. As Clive James has argued in a fine essay on the show ("Fantasy in The West Wing," collected in The Meaning of Recognition [2005]), the dialogue and the debate it engenders sublimate all the other tensions that one might expect in a TV series. I'm not quite saying that The West Wing is (as SF is often accused of being) part of a "literature of ideas"; but it foregrounds engagement with the world, like Bartlet's love of facts, in ways that character-driven drama doesn't usually manage. So the perennially off-on sexual tension between Josh and his assistant Donna is far more interesting to Sorkin when turned into words; only at the very end of the show's run does it start to grudgingly resolve itself. As a final example of Sorkin's faith in words (and his tendency to create Mary Sue-ish writer characters), take a look at "The Portland Trip" from Season 2. Here, Bartlet uses a long plane-flight with Sam and Toby to articulate more clearly than ever the idea that his job is about creating possibility, and writers are the ones who tell the story of how: "You know why late flights are good? Because we cease to be earthbound and burdened with practicality. Ask the impertinent question. Talk about the idea no-one has thought about yet." A perfect credo for science fiction.

Of course, it all had to end, and conventional wisdom says that The West Wing fell apart after Season 4. Lowe left mid-season; Sorkin and his lead director Thomas Schlamme did the same at the end of the season. The creative lead for the last three seasons was John Wells, who had formerly done the same job on ER. What Wells did was to render The West Wing closer to more orthodox drama—for many, including myself, damagingly so. The fizz of dialogue became flatter, continuity became more rigorously enforced, actions started having longer-term consequences—something Sorkin wasn't always that interested in. The series became, in other words, more scratchable by common sense. Anyone who does persist to the end of the show's run will also have a good deal of darkness to contend with, darkness stemming (I contend) from the show's increasing out-of-stepness with the world we inhabit.

But Wells was also prepared to shuffle the characters away from the roles they were accustomed to. Bartlet fires Leo at the start of Season 6 over a long-fermenting disagreement about Israel, although after a heart attack—brilliantly played by Spencer—Leo is brought back later in a reduced role. CJ succeeds him as Chief of Staff, Josh goes off to work for one of Bartlet's potential successors, Matt Santos, and Toby self-destructs in spectacular fashion. As a result, the last season or two of The West Wing, which largely follow the race to follow Bartlet, have a weirdly emptied-out quality, like wandering through a great house from which all the children have left. Wells's argument, I'm sure, would be that dream teams like those of Seasons 1-4 don't stay together forever, and that their existence tends to exert costs on their members; and that the series was showing this realistically. The real world was getting ready to do the same, though: Spencer died of a heart attack half-way through the filming of Season 7, and a rapidly written funeral for Leo McGarry was inserted into the run. The episode containing it, "Requiem," is heartbreaking. The opening sequence, showing the funeral, brings back guest stars from across the series's run, all sitting silently in black, all crushed by self-evidently real grief. That so many actors would turn out to play low-profile, non-speaking parts for a few seconds shows plainly how much Spencer's loss hurt.

So the obvious advice about the seven seasons of The West Wing—now all available on DVD—is to sample the first if you haven't done already, and see if you're taken by its charms. You may want to proceed with caution from Season 5 on, but I find plenty to value in the later seasons: Wells's efforts at exposing the costs of counterfactuals draws some very fine work from his cast, Whitford and Janney in particular. But you have to watch the series remembering the context in which it was made. Seasons 1 and 2 come from the dying days of the Clinton era, whose end was marked by another great piece of science fiction, The Onion's "Bush: our long national nightmare of peace and prosperity is over." From then on, we're not just in the Bush era but the post-9/11 era. There's a whole other essay to be written on the show's treatment of Islamic terrorism and the Middle East, from the hastily conceived one-off "Isaac and Ishmael" episode that opened the third season to the more serious consequences played out in Season 4, and then the just-like-that solution of the Israeli-Palestinian impasse at the start of Season 6.

In the penultimate episode, CJ pays a surprise visit to her former colleague Toby, now in disgrace and facing jail. They fence a little around the issue of a pardon for him, and around their batch of never-quite-addressed sexual tension. As she's leaving, she says with a smile, "We had it good there for a while." The "we" might be their group of staffers, or their group of actors, or America. Like youth, it's something they know won't ever come back. Toby is pardoned in the final episode, as Bartlet leaves office and his Democrat successor takes over. The final episode is, even more than the earlier ones, a leave-taking whose emptied-out rooms and echoing vacancies reminded me of nothing so much as the last ten minutes of 2001. The ending is the necessary and obvious one, perhaps a bit too literal, perhaps a bit too much part of Wells's sentimental streak—which is at least as obvious as Sorkin's. Leo's daughter returns to the President the "Bartlet for America" napkin, and he opens it as he departs Washington on Air Force One. He looks at it for a moment and passes it to his wife.

"What are you thinking about?" she asks him.

"Tomorrow."

Graham Sleight lives in London, UK. He would like to thank John Clute, Niall Harrison, and Dan Hartland for discussions about The West Wing. The conclusions above are, of course, his own.