Modernism refers to a reforming movement in art, architecture, music, literature and the applied arts during the late 19th Century and early 20th Century. There is no specifically Modernist movement in Philosophy, but rather Modernism refers to a movement within the arts which had some influence over later philosophical thought. The later reaction against Modernism gave rise to the Post-Modernist movement both in the arts and in philosophy.
Modernism was essentially conceived of as a rebellion against 19th Century academic and historicist traditions and against Victorian nationalism and cultural absolutism, on the grounds that the "traditional" forms of art, architecture, literature, religious faith, social organization and daily life (in a modern industrialized world) were becoming outdated. The movement was initially called "avant-garde", descriptive of its attempt to overthrow some aspect of tradition or the status quo. The term "modernism" itself is derived from the Latin "modo", meaning "just now".
It called for the re-examination of every aspect of existence, from commerce to philosophy, with the goal of finding that which was "holding back" progress, and replacing it with new, progressive and better ways of reaching the same end. Modernists believed that by rejecting tradition they could discover radically new ways of making art, and at the same time to force the audience to take the trouble to question their own preconceptions. It stressed freedom of expression, experimentation, radicalism and primitivism, and its disregard for conventional expectations often meant startling and alienating audiences with bizarre and unpredictable effects (e.g. surrealism in art, atonality in music, stream-of-consciousness literature).
Some Modernists saw themselves as part of a revolutionary culture that also included political revolution, while others rejected conventional politics as well as artistic conventions, believing that a revolution of political consciousness had greater importance than a change in actual political structures.
The first wave of Modernism as an artistic umbrella movement broke in the first decade or two of the 20th Century, with ground-breaking works by people like Arthur Schoenberg and Igor Stravinsky in music; Gustav Klimt, Pablo Picasso, Henri Matisse, Marcel Duchamp, Wassily Kandinsky and Piet Mondrian in art; Le Corbusier, Walter Gropius and Mies van der Rohe in architecture; and Guillaume Apollinaire, James Joyce, T. S. Eliot and Virginia Woolf in literature; to mention just a few. The movement came of age in the 1920s, with Bauhaus, Surrealism, Cubism, Fauvism, Futurism and, perhaps the most nihilistic of all, Dada.
After World War II, the focus moved from Europe to the United States, and Abstract Expressionism (led by Jackson Pollock) continued the movement's momentum, followed by movements such as Geometric Abstraction, Minimalism, Process Art, Pop Art and Pop Music.
By the time Modernism had become so institutionalized and mainstream that it was considered "post avant-garde", indicating that it had lost its power as a revolutionary movement, it generated in turn its own reaction, known as Post-Modernism, which was both a response to Modernism and a rediscovery of the value of older forms of art. Modernism remains much more a movement in the arts than in philosophy, although Post-Modernism has a specifically philosophical aspect in addition to the artistic one.