Based on the studies and discussions of the Epistemology Study Group of the Porto Alegre Psychoanalytical Society, the authors aim to connect the notions of psychical determinism with the concept of trauma and temporality, from a perspective of the mind as a complex system. Following consideration of the concept of psychical determinism, they attempt to expand the discussion on causality. They propose that trauma be situated in the body of contemporary psychoanalysis, where emotional experience is favoured over factual events, leading to the need to rethink the concept of trauma and its usefulness. In the same way, in the light of recent developments, the authors revisit the Freudian etiologic equation, with a proposal that an i, for imaginary factor, be included, corresponding to an element of complexity. The question of temporality, connected with trauma and the therapeutic action of psychoanalysis, is approached within a vision of irreversible time, characteristic of complex systems, far-from-equilibrium—which is how the authors understand psychical functioning.