Existentialism, as a philosophy, gained prominence after World War II. Instead of focusing upon a particular aspect of human existence, existentialists argued that our focus must be upon the whole being as he/she exists in the world. Rebelling against the rationalism of such philosophers as Descartes and Hegel, existentialists reject the emphasis placed on man as primarily a thinking being. Freedom is central to human existence, and human relations and encounters cannot be reduced simply to "thinking." This provides—through alphabetically arranged entries—overviews of the various tenets, philosophers, and writers of existentialism, and of those writers/philosophers who, in retrospect, seem to existentialists to espouse their philosophy: Nietzsche, Kierkegaard, Dostoyevski, et al.