Trapped between the caricatured causalities of biological determinism and the sinister abdications of sociological relativism, socio-ecological interdisciplinarity stagnates. It has lost sight of the ambition of a long-term program and no longer works to conduct applied research on the concrete prerequisites for reliable cooperation, despite an accumulation of emergencies. The difficulty lies in the general and prolonged abandonment of necessary procedures under the influence of hidden philosophical presumptions. In the end, ecology, sociology, history, economics, agronomy, etc. are seriously handicapped by the absence of a common epistemology of comparative practice, an absence maintained by the dominant epistemology itself. Social Structures and Natural Systems seeks to demonstrate, with regard to social anthropology and ecology, a scientific compatibility of research subject to methodological requirements that are deductible from the conditions of the existence of science itself. All of this boils down to one observation: this book will be a success if, and only if, it becomes a beginning.