Modernism can be generally placed as an artistic and academic (though mostly artistic) movement occurring in the late 19th and early 20th century. It was a reaction to industrialization, the growth of cities, and, eventually, the effects of World War I. It is important to note that, given this definition, modernism as we understand it is limited to the perspective of Western society—in other words, the United States and Western Europe.
Modernism is full of contradictions, which I attribute to the decentralized nature of its manifestation and to the confusion artists and thinkers faced in a paradigm of their own creation. Since modernism at its core is a rebellion against the “status quo” (which at the time consisted of cultural absolutism, 19th century academic traditions, and the dominance of Western European thinking), modernism naturally took on various, sometimes contradictory, forms because what ‘rebellion’ meant depended on the artist, musician, philosopher, etc. Modernism is more of a mode of thinking, a framework with which to approach philosophy, music, and art, and it’s a mode of thinking which rejects prevailing methods and standards. In this sense, modernism should not have “died” in the early 20th century—it is not a movement that can be isolated to one time-frame, so long as there exists a counterculture movement within a status-quo context. Modernists are those whose words and works bring attention to our preconceived notions. Take, for example, the radical departure from traditional art forms. Artists like Picasso embraced methods and styles of painting that showed how we can still recognize the human form, even when its distorted depiction is nowhere close to what we perceive in reality.
In art, modernism is associated with Expressionism, Cubism, and Futurism, just to name a few. But that assertion is only correct if we limit ourselves to examining the first few decades of the 20th century. Once a modernist endeavor becomes institutionalized, it loses its modernist label. To be modernist is to always exist in a ‘revolutionary state of being.’ Modernism is transient, and those who tie down its occurrence to the late 19th through early 20th century are those who have narrowed modernism only to its first iteration, during the overwhelming public reaction to rapid industrialization, what we could potentially call “First Wave Modernism.”