This book deals with "Phenomenological reduction and existence in Edmund Husserl's Cartesian Meditations". First, we consider René Descartes as a precursor of Husserlian phenomenology. Starting with the doubt developed in his Méditations métaphysiques, he paved the way for transcendental philosophy. Next, we describe Edmund Husserl's phenomenological position, for whom phenomenological reduction is the act by which phenomenology achieves its transcendental dimension, since the residue of this operation is the transcendental ego, having bracketed the natural thesis of the world. Moreover, we have highlighted Edmund Husserl's originality in that he posed the problem of intersubjectivity, so that the transcendental phenomenology he develops is an experience of both the ego and the alter-ego. Phenomenology is, after all, communication with the world, hence the notion of intersubjectivity. It is concerned with individual and collective existence.