When Michael Craig-Martin enrolled at Yale to study fine art in 1961, he was lucky, he says, to hit on "probably the best moment in the art school's history. There were good teachers, but more importantly there were amazing students." Craig-Martin studied alongside Richard Serra, Chuck Close and Brice Marden among others and says he learned then that "becoming an artist is a peer activity".  It was a lesson he carried into his subsequent teaching career, and 25 years later, as a tutor at Goldsmiths College in London, he saw it vindicated in the most spectacular manner. "Any art school teacher will say that rarely a year goes by without coming across someone who is interesting," he says. "But at Goldsmiths in the mid-80s there were five, then 10, then 20 amazingly interesting students who overlapped each other. I didn't make it happen. If there was a formula we'd all be doing it. But I did recognise it and tried to generate an engagement between these remarkable young artists."  As the YBA generation of Damien Hirst, Gary Hume, Sarah Lucas, Anya Gallacio, Mat Collishaw - to name just some of Craig-Martin's students - spilled out of Goldsmiths to remake the British art scene, so Craig-Martin became increasingly influential, and was routinely described as the "Godfather of Britart". "Everyone," as one commentator put it, "listens to Michael."  He also became better known as an artist in both galleries and large public commissions. His most recognised work today is his re-sized and vibrantly coloured graphic outlines of everyday objects such as chairs, cutlery or phones, but his career began, in the 60s, with a series of minimalist boxes. By the 70s he was a leading conceptualist, with his most famous work, An Oak Tree (1973), comprising a glass of water on a shelf accompanied by a text in which he asks himself questions to assert that the glass is in fact an oak tree.  His entire career is brought together this month in a retrospective at the Irish Museum of Modern Art in Dublin, accompanied by a lavish new monograph by Richard Cork (Thames & Hudson). The earliest work on show is his 1963 dissertation film - his only film work, and believed lost for 30 years - which is a series of static shots of the Connemara countryside. "I tried to include ripples on the wheat field, or a chicken next to an abandoned thatched cottage to show that they weren't stills," he explains. "But what that also shows is the presence of people within what might seem a barren landscape. That's always been somewhere in my work, and although I know there have been big changes to my work over the years, looking at it now I can see a continuum."  The Dublin show is something of a homecoming for Craig-Martin, although he has never lived there. His Irish parents were in London during the war, but returned to Dublin for his birth in 1941. His father, Paul, was an agricultural economist at the British ministry of food who went to Washington DC after the war to work for the UN and then the newly founded World Bank. There was little interest in art at home - though, "surprisingly, we had a reproduction of a Picasso blue period painting. But it was still a bit odd when I became very interested in art." With no art taught at his Benedictine school he went, aged 13, to evening and weekend classes in painting. "The minute I learned there was such a thing as the avant-garde, I loved it. The more outrageous the better." At high school he remembers seeing a magazine designed by Duchamp and being "mesmerised that somebody had done something that was so unfamiliar and that I couldn't place".  His time at Yale granted access to a New York art scene that was like "an amazing secret. The abstract expressionists were still alive and working, and then there was this extraordinary outpouring of op art, then pop art, then minimalism. There was new work from Warhol and Jasper Johns, and almost everything would knock your socks off."  From his own generation he identifies Bruce Nauman as "the great artist. He has never been uninteresting. He anticipated everything and he understood everything. In the 60s there was a sense of liberation. But with that liberation came profound difficulties. Nauman, and also people like Richter and Polke, understood the new psychological response, which was a very different idea of where an artwork came from. These people found a way of sustaining an engagement. Art isn't about representing things, it is about acting things out. They acted out the problem of being an artist in the world."  On leaving Yale, Craig-Martin anticipated a career as an artist, but had little expectation of making a living. To make ends meet he taught briefly in New York, before moving to the UK in 1966 to teach at the Bath Academy of Art. Three years later he staged his first one-man show in London and declared himself "speechless and delighted" when the Tate bought Four Identical Boxes with Lids Reversed. His profile raised, he took up posts at Canterbury College of Art and then as artist-in-residence at King's College, Cambridge. Yet he was also subject to the British resistance to modern art and was mocked by Scottish television reporter Fyffe Robertson in 1972, following the definitive Hayward exhibition of British conceptualism, The New Art.  He was, and is, sanguine about such attacks. "The history of art is taking things that previously weren't considered worthy of concern - or maybe even beneath contempt - and pulling them into focus. Naturally people say it is terrible because that had been, until then, a normal and rational response. It takes time for people to accept that these things might be worthy of a closer look." His own foregrounding of everyday objects falls into this category and, as critics have pointed out, just considering the shape of, say, a TV set can lead to considering some of the most fundamental aspects of how a society operates.  "My objects are very simple and well-known images. It's a knife. You don't have to spend any time figuring out whether it's a dagger or maybe a fork. So you can spend all your time on the other parts of it, which in one situation might be something threatening, in another comforting, or any number of meanings. People carry vast amounts of feelings and knowledge about these objects, so I get hugely differing responses from people who might love or hate something for reasons not even they are entirely sure about." He says that, while there was no British art world to speak of when he arrived in the UK, the art schools were "staggeringly important" both as educational institutions and patrons of artists by employing them. He points out how artist-teachers were defined by their art school - "I would never have been offered a job at Camberwell, whereas I was thrilled to be offered one at Goldsmiths" - and praises the freedom and comparatively generous funding of the time. "Some extraordinarily interesting work was done. But such was the indifference to art in the wider world that it was work carried out largely without an audience. Only the toughest and the best, people like Tony Bevan, survived. And it wasn't until Julian Opie became very successful very quickly in the 80s that other students saw there was a possibility of making not only a career, but also money. Then came Damien and his friends."  Despite his apparently secure position within the arts establishment, Craig-Martin says he is pleased that, in part, he still feels like an outsider. "Although a Tate trustee, I will always be someone who was brought up in America." He married in 1963 and had a daughter, but has lived as a gay man since the 70s. He says he is part of - and not part of - the gay world. "I consider myself particularly fortunate to have had the experience of being a father and now a grandfather. But all artists must think of themselves as outsiders and also they must participate in the world. You can't take someone else's feelings and turn them into art. They have to be your feelings and your experiences. You can't make art out of feelings in general. They have to be specific."  Looking back at his career, he says that the Britain in which he arrived in 1966 has "utterly disappeared". Part of that change has been the art boom of the past few decades, but he declares himself "complacent" about such apparently dramatic developments. "I think that everything you gain you lose somewhere else. Our lives are spent trying to improve things, but I think we just make things different. All we do is push things around. You could look at the art world of 20 years ago and say the loss of seriousness has been catastrophic, but the explosion of access has been wonderful. It's just different, not better or worse."  As for the fundamental nature of artistic expression, he believes that is also largely unchanged. If you look at a 15th- or 16th-century painting, he says, you are "not being transported back to the 16th century. You are pulling the painting into now. If you have an art experience, it is a now experience, not a then experience. There is much less difference between the art of the past and present than is popularly thought." He gives the example of walking through room after room in the National Gallery without noticing much, "and then something will just zap you. It is not a history experience or a sociology experience. It is an art experience, and it is the same if the art was made yesterday or 800 years ago. Ultimately, while art has many functions, one of the major ones is to deliver that art experience. It is rare and it is hard. You can't make it happen, and it completely evades some people. But if you want to understand art, you have to look at a lot of art. And the more you look at, the better your chance of experiencing that zap."  Andy Warhol Jasper Johns Bruce Nauman Gerhard Richter Sigmar Polke
A life in art: Michael Craig-Martin, who taught most of the YBAs, is known as the 'Godfather of Britart', and his own work is celebrated in a new retrospective. So why does he feel like an outsider?