 On this view, the relation signified by the reduction-predicate in its basic, or proper use is instantiated by pairs of theories only. A derivative notion of reduction (and, hence, a deviant use of the predicate) allows for statements of the form ‘a reduces to b’ to be true, even if the respective instances of ‘a’ and ‘b’ do not designate theories. The truth of this statement then depends upon a corresponding truth about theory-reduction. For example, if water reduces to H2O, then on this view it does so only if, and if so: in virtue of the fact that folk-chemistry reduces to chemistry.