Tractatus Logico-Philosophicus
Two definitions that were both put forward in the 1920s, however, suggest the range of available opinion. "The world is everything that is the case," wrote Ludwig Wittgenstein in his influential "Tractatus Logico-Philosophicus", first published in 1921. This definition would serve as the basis of logical positivism, with its assumption that there is exactly one world, consisting of the totality of facts, regardless of the interpretations that individual people may make of them.