ABSTRACT
It is the purpose of this paper to show how the classical methodological distinction can be maintained in the face of changing conditions of demand. The solution is, broadly speaking, that (within certain ranges) the separation of the theory of value from the theory of output can be kept beyond the limits set by the so-called 'non-substitution theorem' and that, where this is not possible, characteristic interactions between the determination of the level of output and the determination of prices take place that are in some cases quite different from those discussed in neoclassical theory.
