Our final tradition is the very broad and highly acclaimed one of Critical Theory. This term is often used very loosely to include thinkers like Foucault, the post-structuralists or those influenced by Nietzsche, Marx and Freud, and indeed some even go so far as to apply the term to almost any critical approach to the humanities at all. It should be kept in mind however that in correct usage Critical Theory denotes a very specific tradition.

Critical Theory, properly conceived, is the brainchild of the Early Frankfurt School. It is worth noting the enormous impact of the Early Frankfurt School and critical theory in post war liberal Europe and indeed throughout the world. Held explains that: ‘The writings of what one may loosely refer to as a “school” of western Marxism – critical theory – caught the imagination of students and intellectuals in the 1960's and early 1970's. In Germany thousands of copies of the “school”s’ work were sold, frequently in cheap pirate editions. Members of the New Left in other European countries as well as in North America were often inspired by the same sources. In other parts of the world, for example in Allende's Chile, the influence of these texts could also be detected. In the streets of Santiago Marcuse's name often took a place alongside Marx and Mao in the political slogans of the day. Critical theory became a key element in the formation and self-understanding of the New Left'.