The morning I meet foreign correspondent Patrick Cockburn is, appropriately enough, one that will reverberate in world politics for some time to come. As I step off the train in Canterbury, news has just broken of murders at the offices of Charlie Hebdo. Such is the seriousness of the attack, the location and the nature of the target, it’s immediately clear millions will be drawn into the drama: western governments and their Middle Eastern counterparts, Muslims living unexceptional lives and, indeed, journalists everywhere. A web of reaction and counterreaction, of just the kind Cockburn has spent his life examining, will extend from Washington to Lahore.

Events are still unfolding as I reach his ancient house, half a mile or so from the cathedral, and I explain breathlessly what has happened. “Let’s watch the news for five minutes, and then we’ll talk,” he suggests, wondering whether Sky or the BBC will be better, and settling on the latter. “Of course, there’s often very little to say at times like this, so you end up with a certain amount of speculation.” We watch in silence as video of what appears to be a shootout on a Parisian street is played over and over again. Cockburn sits impassively, absorbing what information there is, then asks me to press the mute button. He calls the newsdesk at the Independent and leaves a message offering to weigh in as needed, particularly if it emerges that there are links with Isis, the subject of his latest book.

My head is swimming, but Cockburn is matter-of-fact. This is, after all, the grim stuff of his trade, albeit a little closer to home than usual. He has reported from the Middle East, with interludes in Moscow and Washington, for 40-odd years. He witnessed the civil war in Lebanon, the first and second Gulf wars, the Afghan war and, more recently, Syria’s descent into bloody chaos. His work includes in-depth studies of Saddam Hussein and Muqtada al-Sadr, and of the US occupation of Iraq. His reporting has earned him the Martha Gellhorn and James Cameron prizes, among others. Quick to size things up, to put them in context, he is precise, methodical, almost detached. I wonder out loud whether the attack on Charlie Hebdo will be treated as a question of law enforcement, rather than an existential challenge to be met with an overwhelming political response. Perhaps it’s a forlorn hope? “It is forlorn,” he says. “Actually this sort of thing is geared towards making sure it’s forlorn. To have an effective terrorist attack, you require the complicity of governments – through creating an overreaction, the collective punishment of communities that are deemed to be responsible, torture, wars and so on. This is true whether it’s the American government after 9/11, or the tsarist government at the end of the 19th century.”

That flash of history – Russian history, no less – reminds us of Cockburn’s roots in a tradition of learned but politically engaged reporting. His father, Claud, was a foreign correspondent for the Times before leaving to found the Week, an anti-fascist newsletter that ran from 1933-41. He was a communist who fought in the Spanish civil war, and sent dispatches to the Daily Worker back in London.

“He was always amazed that other people didn’t take [a radical] position,” recalls Cockburn. “He left Oxford, he went to Germany in the late 1920s, then went to New York to be the Times correspondent at the time of the great crash. Then the Nazis came to power. He used to say: ‘If you didn’t have some radical thoughts after that, you must be pretty intellectually inert.’ I agree.”

Though less parti pris than his father – he tells me he has never been a member of the Communist or any other political party – Cockburn’s formative years also led him to some radical conclusions. “I was brought up in Ireland, which was still very conscious in the 1950s of being a conquered country,” he says. “And my first political experiences and the first time I started writing were in Northern Ireland.” If any overarching insight emerges from his work, it is that the interests of small countries rarely coincide with those of the big countries that seek to dominate them. This does not seem to be an article of faith, but something born out of years of observation. In fact, Cockburn’s views on the question of western military engagement are surprisingly flexible. “There are occasions when you could say that it was a very good thing the Americans intervened. Let’s say, when Kobani was under siege, or when Isis was approaching Erbil and massacring and murdering and raping the Yazidis. Or in Libya, you could say Benghazi. But,” he continues, “the interests of the people in a country are very unlikely to permanently coincide with the occupying power.”

Can such assumptions end up getting in the way of impartial reporting? Here, Cockburn summons up his father’s concept of the “factual heresy”. The idea that journalism can ever be completely free from the prejudices of its practitioners is a fiction, and the way to deliver trustworthy reporting is to be honest about what those prejudices are. “Everybody has an agenda in that they have things that they think are true and things that they think are important, and vice versa,” he says. “There’s a sort of pretence that it’s not so, and that’s fine, but one should also make clear in writing where one’s coming from. That should be apparent.”

A slightly mischievous question tends to hang over writers drawn to the Middle East, for which we could blame Richard Burton and TE Lawrence, among others. Are they intoxicated by it? Do they harbour romantic ideas of the Arab world, all coffee houses and colourful bazaars? It’s a little unfair, but I’m curious to know the nature of Cockburn’s interest, aside from that of being a witness to history, which could equally have taken him to other places. His answer seems a little bloodless at first. “The niche sort of found me. I happened to be in the niche. It was rather accidental.” But then: “I liked cosmopolitan societies. They’re more fun, they’re more interesting, a place like Beirut … the people speak three or four languages. They’re never pacific places, but they’re attractive and there aren’t so many of them now – there used to be Smyrna, in Turkey, there used to be Alexandria, and Baghdad, actually, was rather like that.” I get him to admit that his Irish upbringing – by the rootless son of a diplomat and the daughter of an Ascendancy family – might have given him a taste for the variegated.

Had Cockburn not become a reporter, I suspect he would have been a novelist, or more likely, a historian. Writing is an ingrained habit. He tells me that his father was at his desk by 5am every day. His mother wrote an autobiography, and his brothers became journalists too. As a result, his work encompasses more than just his professional life. In The Broken Boy (2005), he turned his attention not only to postwar Irish public health and the 1956 Cork polio epidemic, but to his family and himself. At six he was a victim of that outbreak, the last before Jonas Salk’s vaccine was introduced in 1957. He suffers the effects of the disease to this day: he cannot run, and walks with a stick, a fact you might imagine would make war reporting difficult. He brushes off the suggestion, joking that lying flat on his face when someone’s shooting at you doesn’t require much physical agility.

Ill health was the spur for another, more devastating family memoir in 2011. Interweaving sections written by Cockburn and his eldest son Henry, it tells the story of the latter’s psychotic breakdown and treatment for schizophrenia. Cockburn was in Kabul when, down a dodgy satellite phone line, his wife Jan told him that Henry had been rescued after swimming across the River Ouse in East Sussex. He was trying to return home from Brighton, at the urging of the “brambles, trees, and wild animals”.

The book is extremely frank about the depredations of an illness that is still poorly understood and highly stigmatised. Cockburn describes his son running away, only to be found hiding in a quarry having soiled himself, and his wife’s desperation and bewilderment at the lack of improvement after the first breakdown. It was a brave decision to lay all this out in public, but also an act of kindness – a way of allowing Henry to make his own contribution in the family tradition. Cockburn tells me the idea came to him when sitting with his son after a clinic appointment. Henry told him he felt a complete failure. His friends all had jobs, degrees, spouses. “So I thought, why not turn this into an asset from his point of view and also give him something to do? And I thought he must write his stuff so it has the authenticity of an eyewitness.” Henry’s doctors didn’t object. “Lots of things he never told me came out when he was writing it. And it was sort of an achievement [for him] as well.”

Henry’s Demons won plaudits for both its authors and was shortlisted for the Costa book award. With it, Cockburn’s reputation as a writer of extraordinary range was cemented. It introduced a new audience to his literary skill and powers of investigation. Since then, however, he has returned to more familiar territory – and universal critical acclaim is likely to give way to time-worn journalistic rows about partiality, blame and sympathy for dictators. In The Rise of Islamic State, Cockburn attempts to disentangle the most recent mess in the Middle East – the semi-collapse of the Syrian and Iraqi states and the renaissance of violent jihadism in the form of Isis, a group he was writing about months before their extraordinary gains in summer 2014 captured the world’s attention.

The story is difficult to unpick: a genuine revolt in Syria against a brutal dictatorship becomes intertwined with a broader sectarian struggle. The problem is compounded by interventions from western powers, Saudi Arabia, Iran, Russia and others. Turkey refuses to shut its borders to extremist adventurers, and the Iraqi army, essentially a machine for corruption, disintegrated at its first real test. But the complexity of the situation should not be used as a get-out clause. “If you emphasise [that], and say everybody’s responsible, you let people off the hook,” argues Cockburn. “I think that one should be very specific as to what’s gone wrong.” He cites the Turkish border, the decision to turn a blind eye to whether support for anti-Assad rebels went to jihadists or non-jihadists, the insistence at the Geneva II peace conference that any solution must involve Assad’s exit. Putting his clear animus for the Syrian president to one side, he believes that demanding he step down is effectively asking for the war to continue. Instead, he thinks every effort should be made to de-escalate, with ceasefires brokered where possible between the government and non-jihadist opposition groups.

As we saw vividly that morning, continued violence in the region has international consequences. Six wars in the Middle East and North Africa – Iraq, Syria, Afghanistan, Yemen, Somalia and Libya – provide an “ideal breeding ground” for attacks like those in Paris, Cockburn says. It has since emerged that the Charlie Hebdo killers had been trained in Yemen, and that the partner of the gunman who murdered four at a kosher supermarket two days later has taken refuge in Syria. “It is inevitable that sparks from these conflicts land in western Europe and other parts of the world,” he says, “leading to assassinations, bombings and kidnappings,” of which we can only expect more. A longer-term solution will involve the west reconsidering its relationship with those regional actors who have done more than any other to nurture extremist ideologies: Pakistan and Saudi Arabia.

In the aftermath of a massacre, many will be deaf to Cockburn’s pleas for a critical eye over foreign powers’ actions and alliances. “This often happens at times of high emotion. An explanation of the roots of some ghastly atrocity such as Charlie Hebdo [is seen] to dilute the degree of evil involved and justify the actions of the perpetrators. This response is understandable but it is not very useful. Asking who is to directly to blame for Charlie Hebdo and explaining why it happened are two different things.”

This is typical Cockburn: politically charged, but not impassioned. Characteristic of a man who, as he turns 65 this year, will continue to report simply “because one’s interested in history, in why things are happening”.