The purpose of this article is to tackle the way postmodernists have attacked science. Departing from the doctrine of relativism, postmodernists have long claimed that science does not deserve any priority over pseudoscientific or even anti-scientific approaches. Regrettably, in the 20th Century, some philosophers were part of this trend. Claude Levi Strauss’ views on rationality and irrationality, Ludwig Wittgenstein’s notion of “language games”, Paul Feyerabend’s epistemological anarchism, and Thomas Kuhn’s theories about paradigms and their incommensurability, are objects of critique in this article. This article also defends some of Karl Popper’s views on the philosophy of science, and addresses the way some postmodernists have erroneously used Popper’s philosophy to advance their own views.