What are the conceptual and normative relationships between trust and sympathy? This paper proposes to ask this question in a critical interpretation of the well-known neo-hobbesian philosopher David Gautier’s main book: Morals by Agreement. It shows that his way to resolve the paradoxes of cooperation in the rational choice theory does not lead him to demonstrate, even in a original fashion, that moral principles are principles of rational choice, but that trust and cooperation imply that personal interests have to transcend themselves in order to create sympathetic bonds and a sense of community between persons. Cooperation and its dilemmas are then best understood if one substitutes a theory of gift relationships to rational choice theory.