In this chapter, the work focuses on the paradigm shift that emerges in Ontology and Ethics. Changes in the anthropocentric paradigm are examined, triggered by systems theory; the so-called ontological turn of Philippe Descola and Viveiros de Castro; the ecocentric movement of deep ecology by Arne Naess; Aldo Leopold’s land ethic; the animal liberation movement of Peter Singer; the biocentrism of Paul Taylor; and the so-called epistemologies of the South, within the framework of South American constitutionalism. In addressing the change in the ontological paradigm, this work adopts the concepts of paradigm as a disciplinary matrix, proposed by Thomas Kuhn, and Foucault’s epistémê, to examine the shifts in the anthropocentric model toward ecocentrism. Based on Enrique Leff’s reflection on the connection between the ecological crisis and the forgetting of the ontology of life, the need for a change in the way of understanding being and life itself is investigated, drawing on the philosophy of Heidegger, who, in the search for the meaning of “being,” returned to the thought of Heraclitus. The theoretical references for the analysis of harmony with nature in the ontology of life are adopted from the evolutionary dialectic of Cirne-Lima and the integral monism of Hans Jonas.