Brian Leftow

The first response to Anselm’s Proslogion argument for God’s existence, Gaunilo’s On Behalf of the Fool, began a tradition of replying to Anselm with parody. I argue that Gaunilo’s original parody fails, show how to remedy its defects, and point out (what seems till now to have been overlooked) that Anselm actually responds to the parody. I show that his response applies too to the amended parody. I then discuss the revised parody, as a sample parody based on a best possible member of a physical kind. I contend that this too fails, because there cannot be best possible members of physical kinds. This response goes back at least to Plantinga, and in reply, parodists have jiggered physical kinds to permit (they claim) a best possible. I consider all possible ways to make this move, though not all possible instances of each way. I argue that they all fail.

This article provides an explanation of Anselm’s understanding of necessity. Anselm did not write much about modality, and what he did write is puzzling. The dominant readings of Anselm see him as having two concepts of necessity, one merely physical or causal, the other logical or “alethic.” This article argues that Anselm has just one concept of necessity, which corresponds best to what is now called broadly logical or absolute necessity, but whose metaphysics is in terms of powers and lacks of power. The rival interpretations of A. D. Smith, Thomas Williams, and Sandra Visser are discussed and criticized in detail.

Western theists agree that God is eternal. But they disagree over what eternality is. This chapter clarifies one view of eternality, that of Boethius, and shows that some aspects of this view are coherent. On Boethius' view, God is not temporal. The chapter first gives a minimal account of what it is to be temporal. This account explains what sets Boethius' view of God's eternality apart from others. It is shown that Boethius' view implies that though God's life is not temporal, there are events in it, and these events have what is typically a temporal property: they occur in a present. The chapter argues that these are coherent claims.

This essay by Brian Leftow provides an account of the nature and extent of God’s freedom. Theists typically believe that God could have done other than He has done. Many think that God gives them gifts He need not have given. Most Western philosophical theologians have held that God had the choice not to create, for instance. While there is general agreement that God has some leeway, there is disagreement over how much He has. The central point is a defense of a voluntarist rather than a rationalist account of the extent of God’s live options: God is not bound to effect the best, where the sort of value in question is nonmoral.

Brian Leftow offers a theory of the possible and the necessary in which God plays the chief role, and a new sort of argument for God's existence. It has become usual to say that a proposition is possible just in case it is true in some 'possible world' (roughly, some complete history a universe might have) and necessary just if it is true in all. Thus much discussion of possibility and necessity since the 1960s has focussed on the nature and existence (or not) of possible worlds. God and Necessity holds that there are no such things, nor any sort of abstract entity. It assigns the metaphysical 'work' such items usually do to God and events in God's mind, and reduces 'broadly logical' modalities to causal modalities, replacing possible worlds in the semantics of modal logic with God and His mental events. Leftow argues that theists are committed to theist modal theories, and that the merits of a theist modal theory provide an argument for God's existence. Historically, almost all theist modal theories base all necessary truth on God's nature. Leftow disagrees: he argues that necessary truths about possible creatures and kinds of creatures are due ultimately to God's unconstrained imagination and choice. On his theory, it is in no sense part of the nature of God that normal zebras have stripes (if that is a necessary truth). Stripy zebras are simply things God thought up, and they have the nature they do simply because that is how God thought of them. Thus Leftow's essay in metaphysics takes a half-step toward Descartes' view of modal truth, and presents a compelling theist theory of necessity and possibility.