In his book on The Scope and Method of Political Economy, John Neville Keynes distinguishes among "a positive science . . . a body of systematized knowledge concerning what is; a normative or regulative science ... a body of systematized knowledge discussing criteria of what ought to be . . . ; an art ... a system of rules for the attainment of a given end" and later comments that "confusion between them is common and has been the source of many mischievous errors". I could not agree more. when I say this, i refer more to the debate inside subject's ( researcher) mind than the larger debate or methodological wars.
Positive economics is in principle independent of any particular ethical position or normative judgments. As Keynes says, it deals with "what is," not with "what ought to be." Its task is to provide a system of generalizations that can be used to make correct predictions about
the consequences of any change in circumstances. Its performance is to be judged by the precision, scope, and conformity with experience of the predictions it yields.
Formal logic and mathematics, which are both tautologies, are essential aids in checking the correctness of reasoning in this case. And the usefulness of the tautologies themselves ultimately depends on the acceptability of the substantive hypotheses that suggest the particular categories into which they organize the refractory empirical phenomena
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