Gottfried Wilhelm Leibniz (1646–1716) was a prolific and influential German philosopher and mathematician. Rawls devotes two lectures in his Lectures on the History of Moral Philosophy to Leibniz, largely in connection to his more extensive discussion of Kant, since Leibniz was, as Rawls observes, “the dominant igure in Germany in philosophy in Kant’s time” (LHMP 105). Rawls holds that Leibniz “fully accepted an orthodox Christian view” but “he confronted and mastered – indeed, contributed to – the new science of his day, making use of it in his philosophical theology” (LHMP 106). A central part of this philosophical theology was to show that Christian faith “is fully compatible with reasonable belief” (LHMP 107).

Leibniz famously held that the world is the best of all possible worlds. This follows from his beliefs that God is the absolutely perfect being and the creator of the world. God created the most perfect world that he was capable of creating. And because he has the perfections of omnipotence and omniscience – he is “able to create any possible world . . . and [knows] all these worlds (their content and possible history), down to the last detail, and [knows] which world is best and why” (LHMP 112) – the best world of which he is capable of creating is the best possible world. Because there are multiple, irreducible perfections, the best possible world is the one which realizes “the most fitting balance of the various perfections. It is not found by seeing which one maximizes the fulfillment of any one principle (or value) taken by itself.” Furthermore, “The most perfect balance of perfections rests with God’s intuitive judgment. We can’t say much about it” (LHMP 110). Thus, Leibniz’s substantive view is a form of pluralism (or “intuitionism” as Rawls uses the term in TJ).