Yes, Malebranche was highly regarded as a theological metaphysician. In his major book, The Search after Truth (1674), he developed his theory of “vision in God.” Malebranche agreed with René Descartes (1596–1650) that ideas in the mind are the basic units of perception and knowledge, but he argued that our ideas are actually in God, rather than in us. This vision in God was especially important for abstract knowledge, according to Malebranche, because universals, mathematical truths, and moral understanding were part of the vision in God. As such, they reflected God’s knowledge of what was eternally true about the world He had created.

In his Treatise on Nature and Grace (1680), Malebranche provided an explanation of how God’s goodness, omnipotence, and omniscience could allow evil in the world. He claimed that God could have created a more perfect world without the known evils of the present one. This more or mostly perfect world, however, would have been more complicated than the world God did create, and creating that world would have contradicted God’s principle of acting in the simplest possible way, according to general laws. This simplicity and generality could also explain the unequal distribution of grace among human beings.