Longhi was one of the few Italian art historians who took a real interest in contemporary art. However, his output in the early and late periods of his long career clearly evidences a complete reversal of attitude on this subject: the young stalwart defender of Futurism is recast into the mature and equally stalwart reprover of all the post-1945 art
movements.

His whole-hearted endorsement in 1913-1914 of Futurism produced an Avant-Garde interpretation of 17th century art. Yet, only three years later, his sensitivity to the geometric and abstract form, previously the chief element in his outlook on the Caravaggio school, is gradually supplanted by a re-evaluation of colour values and the repudiation of the Avant-Garde movement.

He also deeply and personally resented the rising tide of the "rappel a l'ordre". A champion of Impressionism, he is, in the interwar period, an implacable enemy of the fashionable exaltation of Italian 19th-century painting and its nationalistic connotations. He favoured the work of painters such as Carr a and Morandi, capable of re-interpreting in a personal, non-academic way their rapport with tradition.

After the II World War, Longhi remained faithful to his preference for realism in its broadest terms, judging severely the Abstract and Pop Art movements, as well as the overpowering influence of Picasso. He believed that art critics should only adironic towards those critics who interpreted art from an exclusively philosophical sociological point of view.