ker toward the object (180). This movement takes place for Merleau-Ponty not in the mental act but in the body. To Husserl, the "body" is merely another object existing certainly only in the mental act, but to Merleau-Ponty, the thinker's relationship to the physical world is expanded by the inclusion of the body and the body's movement toward objects in the world: "the irreducible and foundational form of intentionality is that which is involved in one's ability to act on the world" (180).
Unlike Merleau-Ponty, Jean-Paul Sartre agrees with Husserl's understanding of intentionality. However, Sartre seems to come to a more stark conclusion with respect to the wall which intentionality places between the thinker and the object in the world: "The tree escapes me and repulses me, and I can no more lose myself in the tree than it can dissolve itself in me [i.e., in his consciousness]. I'm beyond it; it's beyond me" (98).
To the phenomenologist, intentionality is important because it is the focal point for understanding the true nature of existence itself, of truth, of consciousness. The intentionality of the thinker's mental act, to various degrees for the three phenomenologists, is existence, truth, and consciousness. Intentionality for the phenomenologist locates existence or truth in the act of consciousness of the object---which primarily---or even exclusively---exists in the consciousness.
Intentionality is supposed to overcome idealism by placing reality or existence in the mind or the mental act and keeping it there, rather than leaping to the idealist's conclusion that thought necessarily tells us something concrete about the outside world and its external objects (98). Merleau-Ponty seems, of the three, to most effectively use intentionality to overcome solipsism via his emphasis on the body and its relation to the external or social world: "One is situated in a social world which one shares with other subjects who are l...