ARGUMENTS AGAINST MONOTHEISM 159Consider two sorts of exchange as follows:(EX) Y is permissibly interchangeable for X, where X has exchangeable
intrinsic worth, only if Y is of the same species as X.
(EY) Y is permissibly interchangeable for X, where X has exchangeable
intrinsic worth, only if Y is of the same species as X, or if Y is of a
different species than X, where there being things of the species that
Y belongs to is of at least as much intrinsic natural value as there
being things of the species to which X belongs.
The idea, of course, is that (EX) allows only within-species substitutions
whereas (EY) allows between-species replacements. It seems plain that if
anything in the neighborhood of (EX) and (EY) is true, it is (EY). If (EY) is
true, then even if it would be wrong of God to create something of
exchangeable intrinsic worth and then let it go out of existence without
replacing it with something of equal worth, God could allow any number of
species to go out of existence so long as there were appropriate replacements.
And (EY) does not forbid that there be one replacement that belongs to one
species that replaces the members of a number of other species so long as the
one is valuable enough. The sort of replacement that is relevant here might
be, for example, something of high intrinsic worth for things of lower, or
something of unexchangeable intrinsic worth for things of only
exchangeable intrinsic worth.^50
Two things should be noticed here. There is nothing in the notion of
exchangeable intrinsic natural worth that requires, or that forbids, that if
something X that has it, and is replaced by something Y, that X’s having
existed was somehow necessary for Y’s coming to exist, whether Y has
exchangeable intrinsic natural worth or unexchangeable intrinsic natural
worth. Further, as noted earlier, for any world whose members have any
degree of either exchangeable or unexchangeable intrinsic natural worth,
God could create a world possessed of a higher degree.
Unexchangeable natural intrinsic worth
Traditional claims to the effect that something has unexchangeable intrinsic
worth (though not using this language) have found the exchangeable
intrinsic natural worth versus unexchangeable natural worth distinction to
be based on the former lacking, and the latter having, moral worth. This
claim, or one much like it, is at the basis of a respect for persons ethic. This
distinction provides a clear and defensible answer to an otherwise baffling
question: how can one rationally ground any such distinction?