Freud (and later commentators) have failed to explain how the origins of psychoanalytical theory began with a positivist investment without recognizing a dual epistemological commitment: simply, Freud engaged positivism because he believed it generally equated with empiricism, which he valued, and he rejected "philosophy," and, more specifically, Kantianism, because of the associated transcendental qualities of its epistemology. But this simple dismissal belies a deep investment in Kant's formulation of human reason, in which rationality escapes natural cause and thereby bestows humans with cognitive and moral autonomy. Freud also segregated human rationality: he divided the mind between (1) an unconscious grounded in the biological and thus subject to its own laws, and (2) a faculty of autonomous reason, lodged in consciousness and free of natural forces to become the repository of interpretation and free will. Psychoanalysis thus rests upon a basic Kantian construction, whereby reason, through the aid of analytic techniques, provides a detached scrutiny of the natural world, i.e. the unconscious mental domain. Further, sovereign reason becomes the instrument of self-knowing in the pursuit of human perfection. Herein lies the philosophical foundation of psychoanalytic theory, a beguiling paradox in which natural cause and autonomous reason - determinism and freedom - are conjoined despite their apparent logical exclusion.