This thesis is an investigation into the 'paradigm shift' in Critical Theory which I regard as a critical transformation of Adorno's materialist critique of the philosophy of consciousness to Habermas' intersubjective critique of the philosophy of consciousness. It is concerned primarily, though not exclusively with the writings of Theodor Adorno and Jiirgen Habermas. It is the contention of this thesis that the writings of Adorno are of central importance for an adequate understanding of Habermas' reorientation of Critical Theory. Habermas' more recent writings on Adorno, I wish to argue, do not do justice to Adorno's influence. This thesis develops the argument that Habermas' critique of Adorno is implicit in his earliest writings and it is the aim of this thesis to make this critique explicit. While Habermas' critique of the first generation of Critical Theorists, i.e. that they remain, despite their intentions, caught up in the 'Philosophy of Consciousness', is plausible in broad outline, this critique is inadequately worked through. This deficiency is exacerbated by Habermas' tendency to conflate Adorno with Horkheimer and Marcuse. Therefore, despite these writings, it can be maintained that Habermas' has yet to adequately articulate his critical relationship to Adorno. I take this implicit critique to be the determinate negation of Adorno's critique of the philosophy of consciousness. This thesis is not intended as a comprehensive history of the development of critical theory. Rather it concerns three discrete though related areas. In the first instance I reconstruct Adorno's critique of Ursprungsphilosophie and assess its influence on Habermas' conception of Post-metaphysical Thinking. In the second instance I make an excursus into social theory and assess the shifting conceptions of reification and socialization. Finally I reconstruct Adorno's critique of moral philosophy and assess its impact on Habermas and Apel's Discourse Ethics. In conclusion I survey recent Postmodem ethical theories and assess their challenge to the moral philosophies of Critical Theory.