His discussion of certitude is very closely bound up with his treatment of the problem of freedom, but we may indicate here Renouvier’s attitude to Belief and Knowledge, a problem in which he was aided by the work of his friend Jules Lequier,[30] whom he quotes in his second _Essai de Critique générale_. Renouvier considers it advisable to approach the problem of certitude by considering its opposite, doubt. In a famous passage in his second _Essai_ he states the circumstances under which we do not doubt—namely, “when we see, when we know, when we believe.” Owing to our liability to error (even seeing is not believing, and we frequently change our minds even about our “seeing”), it appears that belief is always involved, and more correctly “we believe that we see, we believe that we know.” Belief is a state of consciousness involved in a certain affirmation of which the motives show themselves as adequate. Certitude arises when the possibility of an affirmation of the contrary is entirely rejected by the mind. Certitude thus appears as a kind of belief. All knowledge, Renouvier maintains, involves an affirmation of will. It is here we see the contrast so strongly marked between him and Renan, who wished us to “let things think themselves out in us.” “Every affirmation in which consciousness is reflective is subordinated, in consciousness, to the determination to affirm.” Our knowledge, our certitude, our belief, whatever we prefer to call it, is a construction not purely intellectual but involving elements of feeling and, above all, of will. Even the most logically incontrovertible truth are sometimes unconvincing. This is because certitude is not purely intellectual; it is _une affaire passionnelle_.[31] Renouvier here not only approaches the pragmatist position, but he recalls the attitude to will, assumed by Maine de Biran. For the Cartesian formula De Biran had suggested the substitution of _Volo, ergo sum_. The inadequacy of the the _Cogito, ergo sum_ is remarked upon by Lequier, whose treatment of the question of certainty Renouvier follows. As all demonstration is deductive in character and so requires existing premises, we cannot expect the _première vérité_ to be demonstrable. If, from the or certainty, we must turn to the will to create belief, or certainty, we must turn to the will to create beliefs, for no evidence or previous truths exist for us. The _Cogito, ergo sum_ really does not give us a starting point, as Descartes claimed for it, since there is no proper sequence from _cogito_ to _sum_. Here we have merely two selves, _moi-pensée_ and _moi-objet_. We need a live spark to bridge this gap to unite the two into one complete living self; this is found in _moi-volonté_, in a free act of will. This free act of will affirms the existence of the self by uniting in a synthetic judgment the thinking-self to the object-self. “I refuse,” says Renouvier, quoting Lequier, “to follow the work of a knowledge which would not be mine. I accept the certainty of which I am the author.” The _première vérité_ is a free personal act of faith. Certainty in philosophy or in science reposes ultimately upon freedom and the consciousness of freedom.