Descartes claims in the Third Meditation that ideas of sense might be materially false. While an accurate interpretation of this claim has the potential of providing some valuable insights into Descartes's theory of ideas in general and his understanding of the epistemic status of sensations in particular, the explanation Descartes provides of the material falsity of ideas is itself obscure and misleading, making accurate interpretation difficult. In this paper an interpretation of material falsity is offered which identifies the fault of (...) materially false ideas in the logical incoherence of their objective content. The implications of this interpretation are also discussed. (shrink)