 René Descartes advances his version of the cosmological argument not only as a piece of natural theology that proves God’s existence by natural reason, but also serving an epistemic function of guaranteeing that God could not be deceiving him (Meditations on First Philosophy, Preface &amp; Meditation 3). The cosmological argumentcame under serious assault in the 18th century, first byDavid Hume and then by Immanuel Kant. Hume (1748) attacked both theview of causation presupposed in the argument (that causation is anobjective, productive, necessary power relation that holds between twothings) and the Causal Principle—every contingent being has a cause of its existence—that lies at the heart of the argument. Kant contended that the cosmological argument, in identifying the necessary being, relies on the ontological argument, which in turn is suspect. We will return to these criticisms below.