The study of that which lies outside of or beyond the physical realm; (i.e. outside of the realm of the measurable and indeed the knowable). It aims to know and describe the world in its totality, including everything that is not immediately available to the naked eye. It is in this sense inevitably speculative since it deals with such unknowns and perhaps unknowables as causality, existence, and possibility. As such, both empirical philosophers like David Hume and critical philosophers like Kant, Immanuel have been severe on metaphysics. The term derives from Aristotle and refers to works he wrote after his essays on physics. Aristotle himself did not use the word metaphysics---the subject matter he considered, which has since been labelled metaphysics, he referred to as âfirst philosophyâ. Derrida, Jacques defines deconstruction as a critique of western metaphysics, which seems to mean the whole of western philosophy. In contrast, Deleuze, Gillesâs work might be thought of as a lifelong attempt to discern the physical underpinnings of metaphysics.