  I distinguish two types of reduction within the context of quantum-classical
relations, which I designate "formal" and "empirical". Formal reduction holds
or fails to hold solely by virtue of the mathematical relationship between two
theories; it is therefore a two-place, a priori relation between theories.
Empirical reduction requires one theory to encompass the range of physical
behaviors that are well-modeled in another theory; in a certain sense, it is a
three-place, a posteriori relation connecting the theories and the domain of
physical reality that both serve to describe. Focusing on the relationship
between classical and quantum mechanics, I argue that while certain formal
results concerning singular limits as Planck's constant goes to zero have been
taken to preclude the possibility of reduction between these theories, such
results at most block reduction in the formal sense; little if any reason has
been given for thinking that they block reduction in the empirical sense. I
then briefly outline a strategy for empirical reduction that is suggested by
work on decoherence theory, arguing that this sort of account remains a fully
viable route to the empirical reduction of classical to quantum mechanics and
is unaffected by such singular limits.
