John McTaggart Ellis McTaggart was an English idealist metaphysician. For most of his life McTaggart was a fellow and lecturer in philosophy at Trinity College, Cambridge. He was an exponent of the philosophy of Georg Wilhelm Friedrich Hegel and among the most notable of the British idealists. McTaggart is known for "The Unreality of Time" (1908), in which he argues that time is unreal. The work has been widely discussed through the 20th century and into the 21st.

A subset of absolute idealism, British idealism was a philosophical movement that was influential in Britain from the mid-nineteenth century to the early twentieth century. The leading figures in the movement were T. H. Green (1836–1882), F. H. Bradley (1846–1924), and Bernard Bosanquet (1848–1923). They were succeeded by the second generation of J. H. Muirhead (1855–1940), J. M. E. McTaggart (1866–1925), H. H. Joachim (1868–1938), A. E. Taylor (1869–1945), and R. G. Collingwood (1889–1943). The last major figure in the tradition was G. R. G. Mure (1893–1979). Doctrines of early British idealism so provoked the young Cambridge philosophers G. E. Moore and Bertrand Russell that they began a new philosophical tradition, analytic philosophy.