Descartes splits mind from body. You raise your arm. It feels like one movement. Merleau-Ponty says the split misses how you live in the world through your body.
Cartesian dualism treats the body as an object. Merleau-Ponty says the body is the subject of perception. You do not have a body; you are a body-subject. Perception is not inner representation. It is the body's direct engagement with the world.
The body is not an object. For my body is not an object for me. It is the means by which I have access to the world. The phantom limb is not a memory but a certain manner of being in the world.
— Merleau-Ponty, Phenomenology of Perception (1945)
The body is the opening to the world. The phantom limb shows the lived body persists. You reach for a cup without thinking. The body knows the distance. Dualism cannot explain the seamless action. If the body is the subject, what happens when the body is damaged?
Quick reflection
According to Merleau-Ponty, how is the body different from an object?