 The fourth and final section of Phenomenology explores these three themes, starting with a revision of the concept of the cogito that avoids reducing it to merely episodic psychological fact or elevating it to a universal certainty of myself and my cogitationes. Merleau-Ponty argues that we cannot separate the certainty of our thoughts from that of our perceptions, since to truly perceive is to have confidence in the veracity of one’s perceptions. Furthermore, we are not transparent to ourselves, since our “inner states” are available to us only in a situated and ambiguous way. The genuine cogito, Merleau-Ponty argues, is a cogito “in action”: we do not deduce “I am” from “I think”, but rather the certainty of “I think” rests on the “I am” of existential engagement. More basic than explicit self-consciousness and presupposed by it is an ambiguous mode of self-experience that Merleau-Ponty terms the silent or “tacit” cogito—our pre-reflective and inarticulate grasp on the world and ourselves that becomes explicit and determinate only when it finds expression for itself. The illusions of pure self-possession and transparency—like all apparently “eternal” truths—are the results of acquired or sedimented language and concepts.