The philosophical spirit of trust gives a distinctive stamp to the thought of Paul Ric oe ur and radiates his hermeneutical philosophy and ethics. As an onto -anthropological presupposition, trust does not appear expressly thematized in his work, but it can be investigated in key ethical notions: solicitude and attestation, developed in Himself as Other and in the Philosophy of Will and other texts. The aim of the study is to show this trust as the ground for the internal dynamism of his philosophy, whose ontological-ethical presupposition is the original relationship of the self with the other, expressed in the hermeneutical-hopeful spirit, inseparable from its hermeneutical-critical character.