On the Commutativity of Expansion and Substitution Effects

The reversibility of sequential economic choices concerning production and consumption is addressed. A geometric approach to substitution effects and output/income effects is set forth in terms of vector fields on bundle space. By means of suitable fixing relations the 0-homogeneity of such problems can be circumvented, so as to define global parametrizations of effects, for which Lie brackets measure the departure from commutativity. A couple of propositions are established, assessing the benchmark relevance of homothetic models. Application to Farrell decompositions, as tailored by Bogetoft et al. (2006), results in complete agreement with the results found by such Authors. The theoretical relevance of the approach is thoroughly discussed