In the Western tradition, 20th Century philosophy, often referred to simply as "contemporary philosophy", includes the philosophers and systems that flourished since around 1900. It is often split into the so-called "Analytic" and "Continental" traditions. The former generally includes thinkers such as Bertrand Russell, Gottlob Frege, G.E. Moore, Ludwig Wittgenstein, and W.V.O. Quine. The latter includes the related schools of Existentialism (Martin Heidegger, Jean-Paul Sartre, Simone de Beauvoir), Phenomenology (Edmund Husserl), and Postmodernism (Foucault, Derrida, Deleuze). Political and ethical philosophy also thrived during this period, marked by a notable shift in the usage of the term "liberal". Those defending a strong individualist and free-market notion of liberty (Robert Nozick, Ayn Rand, Friedrich Hayek) are now referred to as Classical Liberals. The term "Liberal" often now refers to those (John Rawls, and Pragmatists such as John Dewey and Richard Rorty) who defend communitarianism, egalitarianism, and/or statism in its various forms. See also: 20th C. Philosophers.