What makes painting modern? Is it abstraction, or depicting the modern world, or a mixture of the two? Painting as a medium should have died out long ago according to some definitions of modern art, and yet people keep at it. What is it that can still give these daubs relevance?

Tate has the answer and it is a surprise. On the evidence of its latest Bankside exhibition, to be truly modern a painter has to be a hamfisted hack. Talented artists need not apply. That must be why Howard Hodgkin, David Hockney and Frank Auerbach have to make do with retrospectives at Tate Britain, while the incredibly unimpressive Indian painter Bhupen Khakhar, who died in 2003, is glorified as an important modern artist in the hallowed – and soon to be even more grandiose – industrial temple that is Tate Modern.

Please don’t think I mean that Khakhar was an ironically “bad” painter who deliberately shunned technical smoothness for sophisticated technical reasons. There is no self-knowing game or provocative crassness going on in his brightly coloured but emotionally inert paintings. He is genuinely just not much good.

What makes this an odd exhibition for Tate Modern to put on is that Khakhar so strongly resembles the kind of British painter it would never let through its doors. He made his name in the 1960s as India’s first pop artist, and by the 80s had developed into a postmodernist storyteller whose big narrative paintings have a jaunty exuberant humour. This is a similar trajectory to the likes of RB Kitaj, Joe Tilson and Tom Phillips – artists who dominated the London scene before the Turner prize and Tate Modern blew away such cobwebs. Khakhar’s paintings made me think particularly of the Scottish artist Stephen Campbell, whose narrative pictures are similarly big and boring.