If music represents the most beautiful pole of human experience, war represents the most horrific. Yet classical music's responses to war regularly count among concert halls' best-loved offerings, so strong and so universal is their message. From great musical juggernauts such as Britten's War Requiem or Shostakovich's Seventh Symphony, Leningrad, down to solo songs by Vaughan Williams and George Butterworth, war and the emotions associated with it crop up time and again among the finest creations of this art form.
It is intriguing then that today, though 24-hour news coverage follows contemporary conflicts around the globe in unprecedented detail, the classical music we hear that responds to war still comes, chiefly, from the past. While pop music has engaged much more directly with issues sparked by the wars of today – take PJ Harvey's Mercury Prize-winning album Let England Shake – classical "art" music seems altogether more recalcitrant about it.
The baritone Simon Keenlyside has just recorded a CD entitled Songs of War. It includes Butterworth's poignant song-cycle A Shropshire Lad, based on poetry by AE Housman, plus music ranging from Vaughan Williams to Kurt Weill. Its most recent composition is a setting of Walt Whitman by Ned Rorem, dating from 1969.
Keenlyside suggests, by way of explanation, that before film and photography were widely available, perhaps poetry and music served their purpose; they provided a response to the human tragedy of war, though not often a depiction of it.
"Many of those poets and soldiers didn't write about the horrors they saw," he says. "Whether that's because they didn't want to, or they wanted to push it away from them, a lot of war poetry is actually about life and about life-affirming things."
Offset by our own awareness and hindsight – for instance, knowing that Butterworth was killed in the Battle of the Somme, at the age of 31 – that life-affirming imagery makes the point by contrast even more effectively.
On the one hand, news coverage on television may have shouldered music and poetry out of the picture. On the other, while televised war reports can draw accusations of being antiseptic, music has a different function: that of connecting directly with the emotions. Should there not still be a role for classical music here? Where are the war requiems for the early 21st century?
In the decade since 9/11, war has never been out of the news. But contemporary composers do not seem to be flocking in droves to tackle its issues. It may be a while before they do. Difficult emotions can require time to process. Earlier this year the premiere took place of Steve Reich's WTC 9/11, a work for string quartet and tape responding to the terrorist attack on New York's twin towers. Reich's family lived close to the site and had a narrow escape – the renowned American composer has acknowledged that he only felt able to address the event in music years later.
That is not always the case, of course. Shostakovich finished his Seventh Symphony and witnessed its premiere while the siege of Leningrad was taking place; Prokofiev wrote his Piano Sonatas Nos 6, 7 and 8 – his War Sonatas – between 1939 and 1944, expressing in apparently abstract music his private emotions regarding Stalin's regime and the German invasion of Russia. And in a way, the predominance of Modernism after the 1940s – the abandonment of traditional tonality and structure – was a response to the Second World War.
Composers such as Sir Peter Maxwell Davies, Sir Harrison Birtwistle and Pierre Boulez turned away from the principles of pre-war composition, rejecting the culture of an era that gave rise to the atrocities they had seen pictured, or experienced first hand, in their formative years.
Some composers are still dealing with the legacy ofthe Second World War. Reich composed his famous Different Trains in 1988; like WTC 9/11 it is for string quartet and tape, employing pre-recorded samples that contrast the trains he took in the US as a child with more sinister vehicles from Europe in the same years and the voices of Holocaust survivors. John Adams, another member of a famous triumvirate of American minimalists (with Reich and Philip Glass), responded to 9/11 in On the Transmigration of Souls, which won him the 2003 Pulitzer Prize. More recently, he looked back at the invention of the nuclear bomb in his opera Doctor Atomic.
Slowly, new pieces are emerging. Later this month, the Huddersfield Contemporary Music Festival will feature the world premiere of Mesopotamia by Richard Barrett, which is inspired by the ancient civilisations of Iraq. Maxwell Davies's String Quartet No 3 is what he has termed "an unpremeditated and spontaneous reaction to the illegal invasion of Iraq". The German composer Rolf Riehm has written a Piano Concerto with electronics in which statistics from the Iraq War are among several text fragments.
But we have yet to hear any high-profile classical work that really tackles the human cost of the conflicts in Iraq or Afghanistan. Is the challenge too daunting, because a climate of hypersensitivity, hysteria and over-reaction has become so prevalent? Would a composer approaching the topic risk being judged exploitative, opportunistic or even politically dangerous? Unlike pop music, which is financially independent by comparison, would an orchestra, opera house or promoter avoid the risk of commissioning or presenting such a work, given their dependence on funding and sponsorship and pleasing those who provide both? The concerns are real: in September, the release of Reich's WTC 9/11 on CD was postponed because the cover photograph sparked a row about the dangers of commercialising the event.
Maybe there's simply a feeling of hopelessness about today's wars – that no amount of new requiems can undo any damage or even help the healing. As Wilfred Owen wrote: "My subject is war and the pity of war. The poetry is in the pity. All a poet can do is warn."
What can a musician do? Not much, Keenlyside says: "We're living in a time of seemingly endless wars and it's not my place to make any comment on the rights and wrongs of that. No one needs to be banged on the head about morality by an opera singer.
"But I wanted to do something, not just watch the news, so I'm trying to raise a little bit of money to help young soldiers who are not much older than my children. They're 22 or 23, coming back hurt, and they have to spend the next 60 or 70 years hurt." He is donating proceeds from the CD to a post-traumatic stress charity, Healing the Wounds.
One thing is certain: what music can do, perhaps better than any other art form, is immerse us in the emotions of another person. It steeps us in feelings beyond our experience and creates at least an illusion that we share them.
"Art reflects with great empathy the pity of the situation, the fact of war," says Keenlyside. "Whenever I'm involved in Britten's marvellous, majestic War Requiem, or the requiems by Fauré, Duruflé or Verdi, does it make any difference? No, it doesn't. But it gives comfort and consolation. I don't know if that is its job – but it is what it does."
'Songs of War' is out now on Sony Classical