"Plantinga argues that together, naturalism and evolution provide an insurmountable ""defeater" for the belief that our cognitive faculties are reliable", i.e., a skeptical argument along the lines of Descartes' evil demon or brain in a vat.Robert T. Pennock contends that as supernatural agents and powers "are above and beyond the natural world and its agents and powers" and "are not constrained by natural laws", only logical impossibilities constrain what a supernatural agent could not do.