Jean-Paul Sartre's philosophy was significantly shaped by major historical events, including World War II and the German occupation of France. These experiences led him to develop existentialist ideas, emphasizing individual freedom, responsibility, and the absurdity of existence. During the war, Sartre collaborated with the Resistance and explored themes of alienation and social criticism in his writings. His post-war philosophy called attention to the human condition and the importance of making authentic choices. Sartre's engagement with political issues and advocacy for social justice further solidified his role as a prominent intellectual voice of his time.