Computability theory came into being as a result of Hilbert s attempts to meet Brouwer s challenges, from an intuitionistc and constructive standpoint, to formalism as a foundation for mathematical practice. Viewed this way, con- structive mathematics should be one vision of computability theory. However, there are fundamental di¤erences between computability theory and construc- tive mathematics: the Church-Turing thesis is a disciplining criterion in the former and not in the latter; and classical logic - particularly, the law of the excluded middle - is not accepted in the latter but freely invoked in the former, especially in proving universal negative propositions. In Computable Economics an eclectic approach is adopted where ...