"I'm well-read.

I'm cultured. I've gone through a classical training. And now I'm fed up of watching three-hour French films about relationships breaking down – there's enough of that in real life. I like spaceships. I like explosions."

Gordon McPherson, head of composition at the Royal Conservatoire of Scotland, writes music about things like spaceships and explosions. His latest piece is called Stunt Doubles and is about, well, Hollywood stunt doubles. Sitting at his desk at the RCS, he peers at me unimpressed when I fail to recognise the silver screen action legends who inspired the work's three movements.

"Seriously? One: Yakima Canutt and the Art of Living Dangerously. Canutt was John Wayne's double, only the best stunt man ever -" McPherson grew up in Dundee and delivers his thoughts in languid east coast drone. "That 1939 Stagecoach trick where he jumps from horse to horse? Spielberg copied it in Raiders of the Lost Ark. My music copies it in a corny way, slowing down to a halt with a Copland-esque rodeo vibe.

"Two: Burt Reynolds's Cosmopolitan, 1972. It's a really sleazy interlude based on the famous full-frontal cover pic. Utter kitsch. Three: Bud Elkins and his Incredible Leap to Freedom." I know this one: Elkins was Steve McQueen's double, the one who did the motorbike jump in The Great Escape. "Right. Except that stunt is, ironically, a bit of a let-down - Which may be reflected in the music. Mostly it's an homage to Elmer Bernstein, plenty of snare drum."

There's a theory, and something of a point of principle, behind McPherson's choice of subject matter. "Poets discover the big ideas in their teens then tend to grow out of it," he explains. "That's not so much the case for artists who work in abstract forms. They tend to continue treating the big stuff, earnestly setting TS Eliot and Emily Dickinson and talking about how big the sky is and Greek mythology. It's frowned upon to treat mundane or personal things in serious music."

And no, the spaceships and explosions haven't always earned unanimous approval. McPherson tells me (with some glee) about a reviewer who described one of his pieces as questionable in its entire premise, and about the arguments he faces from other composers and academics. "I was once giving a talk about a piece called Detours, which is about ex-girlfriends and cars. One of the professors told me that music can't be about anything; I told him that yes it can because I wrote it that way. He asked why he should care about my ex-girlfriends; I asked him whether he'd ever had an ex-girlfriend. The point is not my ex-girlfriends – it's the general concept of ex-girlfriends."

So there is a broader meaning, then, maybe even something vaguely akin to big stuff? "OK, you can always impose a highbrow intellectual angle if you want to," he shrugs. "It's usually there, I just don't wear it on my sleeve. Look at The Waterworks [an hour-long "paranoid concerto" he wrote for the Paragon Ensemble in 2003]. That was ostensibly about alien abductions and conspiracy theories but underlying it all was an exploration of belief systems."

Stunt Doubles is scored for sextet and virtual sextet; each instrument has its own midi stunt double that performs technically impossible feats while the real players deal with parts that are simply- "er, let's say tricky". McPherson denies that the piece is any kind of treatise on the plight of modern musicians against technology or the relationship between reality and media-construed ideals. He does concede that it raises "an issue about what's happening in live music at the moment".

"I'm weird about live music," he goes on. "I divorce myself from my pieces the minute I've written them. I'm not a great promoter. Once a piece is finished I won't take it on holiday with me, as it were." And that, he says, is a cultural thing. "A working-class Dundee thing, specifically. A north-east thing. Growing up in Dundee in the 1970s, you could hardly call it cosmopolitan. So when you're thrown into a more cosmopolitan world you have to be quite self-critical."

McPherson started playing the accordion as a teenager – "we lived in a tenement and couldn't get a piano up the stairs" – and by the time he went to York University he knew a lot about post-1950 classical accordion repertoire, but not much by way of the classics. That might explain why his stance on contemporary music performance remains controversially segregated; new works should be played alongside other contemporary music, he says, not shoehorned into traditional classical programmes.

Stunt Doubles was commissioned by Manchester-based contemporary music ensemble Psappha to mark their 20th-anniversary season. It will be premiered in a programme that also includes new American minimalism from Princeton-based composer Sean Friar, and the Scottish premiere of Steve Reich's Double Sextet. "The fact that Reich wrote for the same line-up is a total coincidence," says McPherson, who has been mulling over Stunt Doubles for a few years. "Personally I think his music sounds the same as it has done for the last 20 years. Nice enough, but doesn't really engage me. How do I feel about having my premiere on the programme? Great if it gets the punters in."

Psappha premieres Gordon McPherson's Stunt Doubles at the Royal Conservatoire of Scotland tomorrow.