What else would two Irish people be doing on a bright, sunny morning other than talking about ghosts and the paranormal?Conor McPherson and I are sitting in one of the Gate Theatre’s lovely, time-worn period rooms with large Georgian windows that face out on to Parnell Square in Dublin.I have just asked McPherson, whose play The Weir is among several of his to have had a long through line of the supernatural, if he believes that events can happen in ways we don’t understand.Like every question I put to him over the course of an hour or so, he considers it carefully, frowning unselfconsciously now and then. He is consistently thoughtful, taking time to pause between answers. He may have had decades of experience of being interviewed, but it’s not a process he appears either to be jaded by or to take for granted. At one point he asks, with noticeable anxiety, “Was that an okay answer?”On the supernatural, he says, “I think we live in a situation we can’t understand, and that we know nothing really about – where we came from, why are we conscious, what does it mean to know you are alive and know that you will die? That is the context of our life, and there is no getting away from it.“I think we fill our lives with lots of illusions and distractions and, hopefully, if you are lucky in life, pleasant experiences. The truth is, none of us know what is going on, whatsoever.”He makes a connection between the lacunae of our understanding of the world and his work as a playwright.“The stage is a great metaphor for that: there is this pool of light in the darkness where something is happening. That’s what life is like. As a playwright I am as interested in the darkness around the stage as I am in the pool of light. “I think you are always trying to drag the darkness on to the stage somehow, because that’s really what it’s about. That’s where the truth is somewhere, and we’ll never know it.”McPherson is 54. He was born in Dublin, where he still lives with his wife, the artist Fionnuala Ní Chiosáin, and their daughter. He has been working creatively and in theatre since 1992, both as a writer and as a director. Among his plays are This Lime Tree Bower, The Weir, Port Authority, The Night Alive and the musical Girl from the North Country, based on Bob Dylan songs. He has also written screenplays and adapted several classics, such as Daphne du Maurier’s The Birds, Chekhov’s Uncle Vanya and a stage version of The Hunger Games. He wrote The Weir when he was 26. It opened at the Royal Court Theatre in London in 1997 and at once became a sensation, as he did.McPherson almost didn’t make it out of his 20s. In the midst of his astonishing success, he drank to excess. On February 22nd, 2001, the day Port Authority premiered at the Ambassadors Theatre in London, his pancreas ruptured. Instead of attending the opening night, he was battling with mortality at a London hospital, where he remained for several weeks. He has been sober ever since.The Brightening Air, which premeried at the Old Vic in London last year, was his first new play for 12 years. It begins a run at the Gate this month. The play follows a starry revival of The Weir at the 3Olympia in Dublin last year, when the Oscar nominee Brendan Gleeson featured in the main role. Brian Cox, who starred as Logan Roy in Succession, and who has won many acting awards, including an Emmy, a Golden Globe and two Baftas, was in the original productions of both Dublin Carol and St Nicholas.Brendan Gleeson in The Weir. Photograph: Rich Gilligan