From 1964 to 2012, Christopher Alexander’s theoretical work exhibits an intellectual evolution, from first order to second-order cybernetics, culminating in an ontology of life. Situated at the crossroads of systems thinking and design theory, this article examines this epistemological trajectory to elucidate its transformative implications for the conception of the built environment and to advance a renewed systemic interpretation of generative design in architecture and urbanism. The research undertakes a chronological and thematic analysis of Alexander’s writings, employing a comparative mapping of his conceptual framework against first- and second-order cybernetics and confronting key concepts, from the decomposition of form and feedback mechanisms to pattern languages and generative grammars, with central principles of cybernetic theory. This analytical approach reveals how his thought evolved from a computational model of design toward a systemic understanding of morphogenesis and self-organization. The analysis evidences a paradigmatic transition from a control-oriented conception of design to one grounded in co-creation and emergence. While his early work emphasized hierarchical problem decomposition, his later writings conceive architecture as an evolving living system. This progression culminates in a generative methodology that privileges the organic emergence of form, as an expression of an ontology of life responsive to context, over the prescriptive application of rules. Alexander’s body of literature articulates a framework for holistic and ethically grounded generative design capable of fostering adaptive and resilient environments. It reasserts systems thinking as a guiding epistemic paradigm for architectural practice in the digital age and establishes an ethical imperative for the reflective integration of artificial intelligence within AI-driven and generative design processes.