Maybe it's happened to you too. About two years ago, a stranger sitting next to me leaned over during a particularly banal speech by a high-powered vice-chancellor and whispered "True dat". In two words, my fellow sufferer communicated not only that they watched the cult television series The Wire, but also that they had imbibed its critique of power and corruption in the faltering institutions of state and civil society, its contempt for the idiocy of our leaders, all just expressed in that fatalistic phrase of the foot soldiers of the Baltimore drug war. Clever.

About a year later, it happened again. In the midst of a committee meeting, someone complained about the "frakking regulations". Within two minutes, as if led by mental association, the chair wondered aloud whether a particular dead-eyed bureaucrat was a Cylon. Most people laughed. Most people in the room, I realised, were like me working through the DVDs of Battlestar Galactica. Cylons look like us and talk like us, but are machines: frakking toasters.

Every academic, it seems, always has a DVD box set on the go.

Sometimes you can tell. For a while no one "filled up a photocopier": after The Wire you needed to "re-up the paper stash". A colleague usually greets me in the corridor with the opening "Let me ask you a question..." in that ominous way that Larry David has when he is about to say something catastrophically insulting in Curb Your Enthusiasm.

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You can't always tell, of course. As far as I can see, Mad Men has sadly had no discernible effect on male academic dress. But Sarah Lund's infamous jumper from The Killing opened the floodgates on complicated knitwear in college corridors. And everyone might be watching In Treatment, but in humanities departments we all like to think we're sophisticated psychoanalysts already, so it's impossible to tell. Unless they affect a limp. Then they're probably watching House.

What is it about the habit of watching television series through box sets that provides so much pleasurable diversion from academic life? And will "diversion" really grasp the matter? Maybe it's time I addressed my addiction, particularly as this format begins its rapid fading away in the face of downloads and online streaming. As Georg Hegel said, the owl of Minerva flies at dusk, meaning we only reach understanding as something passes away. Hegel wasn't too keen on Happy Days, I understand.

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The box-set format arose as television splintered into innumerable digital channels, and free-to-air services rapidly emptied of valuable content. Somewhere before the end of The X-Files and early on in The Sopranos, it was no longer possible to trust that channels would keep faith in a stable time-slot, and certainly not in prime time. Before hard-drive recorders, it became easier to wait for the box set and control your own destiny, free from ad breaks and jittery schedulers.

What is sometimes called "appointment" or "event" television vanished for a time. It is significant that the decade of the triumph of the box set (2000-09) coincided almost exactly with the lifespan of Channel 4's Big Brother: one was closed, serial, finite and reassuringly expensive; the other open, random, potentially infinite and pretty cheap.

If "event" telly has returned, it is in the struggle for early Saturday night audiences, and only by reanimating the corpses of variety shows such as Opportunity Knocks or The Generation Game and dressing them up as interminable song-and-dance-offs. Except for these cynically manufactured occasions, we rarely watch TV communally any more, although we might painfully try to regenerate the community we feel we have lost by sitting alone and texting sarcastic comments to strangers on Twitter. Do TV executives still dream of "water-cooler" shows? Well, our water cooler disappeared in the first round of cuts.

Meanwhile, BBC Four scored a couple of notable minor hits by impersonating DVD viewing habits, showing double bills of The Killing (grubby Danish police noir) or Spiral (grubby French police noir) at the daring hour of 9pm. The channel found a neat balance between the rhythms of private DVD binge viewing and the restraint of weekly scheduling. The Guardian began carrying the advisory column "Your next box set" and the journalist Sam Leith worried that there were now too many box sets to have informed critical opinions about. Yet such TV successes rarely last before series are bought up and imprisoned behind pay-TV firewalls (bye-bye Mad Men). At that point, they are hyped up, tossed around in high-speed spin cycles and horribly stained with ad breaks. Hard-drive PVRs (personal video recorders) can solve that, or we can stream episodes on tablet computers, or - already old school - we can wait for the DVD.

I gather that young people and those whose computer skills extend beyond taking the name of Bill Gates in vain when something goes wrong, do this thing called "torrenting". It is possible to find most TV shows uploaded illegally, almost immediately, somewhere on the internet. Yet there is a curious pleasure in waiting, in mapping release dates, in puzzling over the months or even years of delay between US and UK releases. A multi-region player that can play US DVDs has assisted me in truly desperate situations, such as the intolerable prospect of waiting for Seasons 4 and 5 of The Wire, David Simon's mini-series on Iraq - Generation Kill - or the complete run of Twin Peaks, which took years before it was released in the UK. My latest import, I have to confess with some embarrassment, is the deeply rubbish yet compulsive US spy show Burn Notice ("What is the reason for the success of your series?" the creator Matt Nix is asked in one of the DVD's extra features. "WE BLOW STUFF UP," he shouts in reply).

Maybe it's time to categorise my viewing. There is mindless diversion, of course: a necessity sometimes after a long day of watching PowerPoint presentations about quality assurance or a man from the research excellence framework office mumbling obscurely about impact. There are throwaway series that go in one eye and out the other: I favour Burn Notice slightly over True Blood right now. It has enough wit and knowingness to save itself. It also has the cult B-movie actor Bruce Campbell in a consistently hilarious, scene-stealing role. I always have long-cherished comedy shows on cycles of repeat: Seinfeld and Curb Your Enthusiasm have been mainstays for years. Latterly, 20-minute blasts of Tina Fey's 30 Rock can clear some cobwebs, and her struggle with the mad directives of her lunatic corporate bosses somehow seems to resonate with our times.

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I don't really do British telly. It's not just the need for some allure of difference, it's that the structure of US investment in the cultural industry of television seems to create more niches for value amid the boundless rubbish. The US system has generated the great, long, immersive narratives of our time. I have proved intensely allergic to most "serious" British television. For all the great fanfare, our great dramatists - David Hare or Stephen Poliakoff, say - only ever produce filmed plays, breathtakingly illiterate to televisual form, in my opinion. I got the whole way through BBC Two's The Shadow Line this summer, which had some great moments and performances, but the script vanished into parody Pinter, the pall of the theatre stifling the series. Preserve us from the ponderous gravitas of British "issue" drama or the latest reiteration of Upstairs, Downstairs. Give me David Caruso's raised eyebrow and pregnant pause on CSI: Miami any day.

I don't do nostalgia, either. I don't use the DVD form to return to old classics from my childhood. I knew that Minder and The Professionals were rubbish when I was a kid: those programmes aren't for DVDs, but for eternal daytime TV reruns. I did glimpse that the BBC had released The Omega Factor from 1979 on DVD recently, a series about weird psychical and spooky phenomena that terrified me for years, and contributed towards the direction of my historical interests in the Victorian supernatural. But if I watched it again, it would be terrible, wouldn't it? Amusingly, in returning to watch Alec Guinness in the BBC's 1979 version of Tinker, Tailor, Soldier, Spy recently to work out my dissatisfaction with Tomas Alfredson's overrated film, only the opening and closing credits produced that Proustian moment of recall: I clearly scarpered for the duration of such incomprehensible stuff the first time around.

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I am a scholar of the Gothic and science fiction literature and film, but it is precisely this day job, perhaps, that means I tend to leave these TV series alone. I am not a Trekkie, I would not volunteer to watch the revamped Dr Who, and I never got lost in Lost. It is undoubtedly the case that Joss Whedon, the creator of Buffy the Vampire Slayer, Angel and the deeply odd Dollhouse, is one of the greatest televisual minds at work currently, but I've never reached quite the level of passionate fandom that surrounds his work. I have friends who lock themselves away for marathon serial viewing, whole Buffy or Angel series in one weekend. I stand on the fringes of intense discussions at academic conferences about the brilliance of Babylon 5 or Farscape, but I have never watched them. Having been hooked early on by The X-Files and then worked out my position in po-faced academic essays about the show, I am more self-protective about that compulsive academic tendency to turn leisure time back into intellectual labour. When that starts happening, I reach for Burn Notice.

But there is still serious cultural work done by television series. The central triumph of the DVD era has really been the long narrative forms - mainly produced by the cable television network HBO - that give almost complete artistic freedom to teams of trusted writers and produced the phenomenon of what television studies call American Quality Television. These are series that allow the density of the novel form and a transgressive licence that comes with being funded by private cable subscription rather than fearful and conservative advertisers.

For me, the sense of the wholly new things that television could do started with Twin Peaks, that global craze of 1990-91. The series, conceived by David Lynch, was of course on mainstream US television and the producers effectively killed it by demanding early resolution of the murder mystery. Even so, it was remarkable that Lynch could get the comic and horrifying, the mythic and the domestic, explicit violence and devastating grief, to mix to such mercurial effect on prime-time television.

It set a framework for some of what followed. The Sopranos began with the same queasy and surreal mixture of high comedy and graphic violence. We sympathise with Tony Soprano, his panic attacks and horrible mother, and follow him through his therapy for anxiety and depression, but he is also a mob boss who can explode in psychotic and tribal violence. This wrench of emotions and moral turmoil has become a common, discomforting device.

One of the more extraordinary series I've just worked through is Breaking Bad, a story of the economic crash if ever there was one, about a benign, middle-class chemistry school-teacher diagnosed with lung cancer who in desperation to pay medical bills becomes a cook of crystal meth and inadvertently a drug lord forced to commit atrocious violence. It is sometimes jaw-dropping in its moral perversity and is one of the best explorations of contemporary America that I have seen.

Every critic reaches for superlatives when it comes to David Simon's series, The Wire, the work of a writer who combines the detective genre with Greek tragedy, immersive melodramatic narrative with brilliant institutional critique. It lives and breathes as an entirely immersive world. His latest project, Treme, has a looser, improvised feel, but is similarly driven by fierce political engagement.

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Professors are supposed to lament the decline of public sphere culture. Instead, I'm often left asking how, against the odds, did telly get so wise?