Being and Time | Study Guide

Martin Heidegger's Being and Time is among the most influential texts of 20th-century European philosophy. In it, Heidegger rethinks the "meaning of being" in a way that places humans and their experience of the world front and center. He challenges traditional western theories of being, including those of the ancient Greeks, and suggests that any full account of what it means to "be" must include an account of what it means to be human, as opposed to what it means to "be" a rock or a cloud, for example.

In the second half of the book, Heidegger turns to the question of how Dasein—the special kind of being possessed by humans—interacts with the concept of time. To Heidegger, Dasein is not merely a quality, like height or age: it is fundamental enough that in many ways it "is" the person. Accordingly, Heidegger will often focus on what "Dasein is" or "Dasein does," phrases which can be interpreted as referring to the instance of Dasein possessed by any given person. He argues that time serves as a "horizon" of human possibilities and that mortality marks the border beyond which Dasein is "impossible." In order to live authentically, he contends, one must take into account the temporality of one's existence. Being and Time was influential—and controversial—in its time, at least partly because it proposed such a sweeping change of direction for ontology (the philosophical study of being). It remains one of the cornerstone works of this discipline.