There has always been an intense debate in economics concerning its nature (deductive or inductive, "soft" or "hard" science…) and the type of the laws its method could uncover. Beneath there is also a deeper debate on the type of discipline that economics should try to emulate: mathematics, logics, physics, biology or history, even philosophy (see Kolm, 1986). Most economists would agree that the discipline should be a nomological science — one that produces universal laws — but there is less consensus regarding the nature of those laws and how they relate to reality (Lawson, 1997, 2003). There is actually less consensus than expected even among so-called mainstream economists. Some consider indeed that economics is just a branch of (applied, but here also a debate is possible) mathematics (see Rosenberg, 1992; Debreu, 1991). The real economies are so complicated that only a Platonician approach with deductions from axioms of individual rationality could be used to establish simple laws relating economic variables ceteris paribus (Albert, 1970). These laws are time-invariant and valid under a very precise set of assumptions (the latter could be rather unrealistic if the derived predictions make sense, following Friedman's point of view, see Friedman, 1953). We find here among economists two different views regarding the empirical relevance of such deduced laws: for a part of the profession such laws are purely logical ones, with no necessary direct empirical measurable counterparts (Debreu in a sense defends such a position; it is also the case of people working on social choices or economic justice, aiming at a so-called normative science) but for another part of the profession such derived laws should be testable (i.e. the implied variables should have empirical, measurable counterparts, see for example Beckerian's economics). The difference here is between a pure axiomatic approach (Stigum, 1990) that views economics as logics or mathematics or even political philosophy (not an empirical science) and a more realist point of view (the deductive approach should tell us things that otherwise would have remained hidden, but that are still measurable or testable); in other words between a view of economics as "pure theory "  and of economics as an applied science (even if, as physics, grounded on a consistent mathematical theory). These laws that can be deduced from a body of axioms should be tested once the context has been checked by using measurement (the quantitative aspect—using econometrics).