A new art exhibition in London purports to show striking parallels between so-called “outsider art” often created by the mentally ill and some of the 20th century’s greatest “insider” artists. A simple enough concept, but it has at least one critic furious: “A show of ‘outsider’ art… is well worth doing. Nor is it wrong to point out that, in the 20th century, mainstream artists have been fascinated by this kind of art. What is objectionable is to present the art of people with severe mental illness alongside the work of Francis Bacon, Joan Miró or Francis Picabia, and then to propose that there is no essential difference between the two, that both are simply different manifestations of modernity. This is post-modernist crap.”