 For Merleau-Ponty, this “unjustifiable certitude of a sensible world” is the starting point for developing an alternative account of perception, the world, intersubjective relations, and ultimately being as such. Neither the natural sciences nor psychology provide an adequate clarification of this perceptual faith, since they rely on it without acknowledgment even as their theoretical constructions rule out its possibility. Philosophies of reflection, exemplified by Descartes and Kant, also fail in their account of perception, since they reduce the perceived world to an idea, equate the subject with thought, and undermine any understanding of intersubjectivity or a world shared in common (V&amp;I: 62/39, 67/43).