The doctrine of the Trinity maintains that there are exactly three divine Persons (Father, Son, and Holy Spirit) but only one God. The philosophical problem raised by this doctrine is well known. On the one hand, the doctrine seems clearly to imply that the divine Persons are numerically distinct. How else could they be ’three’ rather than one? On the other hand, it seems to imply that Father, Son, and Holy Spirit are identical. If each Person is divine, how else (...) could there be exactly ’one’ God? But the divine Persons can’t be both distinct and identical. Thus, the doctrine appears to be incoherent. Some try to solve this problem by appeal to the view that identity is sortal-relative. In this paper, I argue that this strategy is unsuccessful as a stand-alone solution to the problem of the Trinity. (shrink)

I argue for the consistency of frege's treatments of identity and number. Specifically, I argue that geach is wrong in suggesting that frege's insights about number should have led him to the doctrine of relative identity.

La relation d'identité est-elle univoque, ou est-elle au contraire relative au concept sous lequel le jugement est énoncé? Depuis quelques années, parmi les philosophes anglo-américains, partisans et adversaires de la thèse que l'on a appelée « la relativité de l'identité », se sont affrontés sur ce point.

G.E. Moore's Principia Ethica of 1903 is often considered a revolutionary work that set a new agenda for 20 th-century ethics. This historical view is hard to sustain, however. In metaethics Moore's non naturalist position was close to that defended by Henry Sidgwick and other late..

The doctrine of the Trinity is central to mainstream Christianity. But insofar as it posits “three persons” (Father, Son and Holy Spirit), who are “one God,” it appears as inconsistent as the claim that 1+1+1=1. -/- Much of the literature on “The Logical Problem of the Trinity,” as this has been called, attacks or defends Trinitarianism with little regard to the fourth century theological controversies and the late Hellenistic and early Medieval philosophical background in which it took shape. I argue (...) that this methodol- ogy, which I call “the Puzzle Approach,” produces obviously invalid arguments, and it is unclear how to repair it without collapsing into my preferred method- ology, “the Historical Approach,” which sees history as essential to the debate. I also discuss “mysterianism,” arguing that, successful or not, it has a different goal from the other approaches. I further argue that any solution from the His- torical Approach satisfies the concerns of the Puzzle Approach and mysterianism anyway. -/- I then examine the solution to the Logical Problem of the Trinity found in St. Gregory of Nyssa’s writings, both due to his place in the history of the doctrine, and his clarity in explicating what I call “the metaphysics of synergy.” I recast his solution in standard predicate logic and provide a formal proof of its consistency. I end by considering the possibilities for attacking the broader philosophical context of his defense and conclude that the prospects for doing so are dim. In any case, if there should turn out to be any problem with the doctrine of the Trinity at all, it will not be one of mere logical inconsistency in saying that “These Three are One.”. (shrink)