the problem with scepticism with avant-garde painting has much to do with the frustration of those who expect painting to be only realistic figurative. Much of the avant-garde painting needs to be understood to be appreciated, and, consequently, be first explained and studied . It is not as easy to appreciate as a Velazquez’s painting, which is certainly superb, but that can be partially understood without knowing much about painting. Picasso’s (together with Braque and Gris) greater contribution to the history of painting is certainly his cubist approach –the strongest and boldest critique to realistic figurative representation performed in a period of five centuries and, likely, the turning point in the discipline. Many of what was done thereafter has some kind of relation to cubism in one way or other –apart from the abstract expressionist trend, truly initiated by Kandinsky in the second decade of the twentieth century almost contemporary with synthetic cubism and popularised and vindicated decades later by American painters.
As for the Guernica –and trying to detach it from its political vindication if that is possible- as much of Picasso’s paintings and language is clearly indebted to cubism although it is not a cubist painting at all. If I wanted to persuade anyone about its pictorial true value I would recommend to see the many sketches that were needed even for the master to achieve the expressivity the figures depicted in it attain some of which may be observed in the same exhibit room as the painting at the Reina Sofia Museum in Madrid; also the series of photographs taken by Dora Maar while it was being painted in Picasso’s studio. Apart from that, probably watching the film by Clouzot, ‘The Mystery of Picasso’, –especially the last part where Picasso shows al the paintings that are contained in one painting and the modern notion of process- could also be of help.