According to a traditional view, logical validity consists in nec-
essary truth preservation. Such an account has been argued to carry an
apparent commitment to a unique property of truth to be preserved from
premises to conclusion. Recent discussions, however, have concluded that
if the metaphor of truth preservation is carefully unpacked, no need for
a unique property is there. All is needed is that certain structural rela-
tions among instantiations of truth properties hold. Against this view, we
argue that a unique general truth property is indeed required by logical
validity. We first show that the unpacking should be correctly understood,
since it imposes constraints on the concept and the properties of truth.
We then demonstrate that, under such constraints, a general property is
not imposed by truth preservation but by another feature of validity: its
uniformity. Finally, some options that could be attempted to resist this
result are discussed, showing that (strong) truth pluralism and deflationism
are affected in different ways.
