In his introduction to the revised edition of Man, Economy, and State, Rothbard touches on the chimera of calculation as employed by the so-called “economists” who guide public policy worldwide:

The only place where we can find economics treated with any degree of breadth is in the elementary textbooks. These textbooks, however, are sorry substitutes for a genuine Principles. Since they must, by their nature, present only currently received doctrine, their work is uninteresting to the established economist. Furthermore, since they may only boil down the existing literature, they must of necessity present to the student a hodgepodge of fragmented chapters, each with little or no relation to the other.

Many economists see no loss in all this; in fact, they herald these developments as signs of the enormous progress the science has made on all fronts. Knowledge has grown so vast that no man can encompass it all. Yet economists should at least be responsible for knowing economics — the essentials of the body of their discipline. Certainly, then, these essentials could have been presented by this time. The plain fact is that economics is fragmented precisely because it is no longer regarded as an edifice; since it is considered a congeries of isolated splinters, it is treated as such.

Up until the present Era of the Technocrat, economics was easily explicable, as well as accessible, to the average Joe:

Perhaps the key to this change is that formerly economics was regarded as a logical structure. Fundamentally, whatever the differences of degree, or even of proclaimed methodology, economics was considered a deductive science using verbal logic. Grounded on a few axioms, the edifice of economic thought was deduced step by step. Even when the analysis was primitive or the announced methodology far more inductive, this was the essence of economics during the 19th century. Hence, the treatise on economic “principles” — for if economics proceeds by deductive logic grounded on a few simple and evident axioms, then the corpus of economics can be presented as an interrelated whole to the intelligent layman with no loss of ultimate rigor. The layman is taken step by step from simple and evident truths to more complex and less evident ones.

The “Austrians” were — and still are — foremost in employing and confirming this paradigm:

The “Austrian” economists best perceived this method and used it most fully and cogently. They were the classic employers, in short, of the “praxeologic” method. In the present day, however, the prevailing epistemology has thrown over praxeology for methods at once too empirical and too “theoretical.” Empiricism has disintegrated economics to such an extent that no one thinks to look for a complete edifice; and, paradoxically, it has falsified economics by making economists eager to introduce admittedly false and short-cut assumptions in order to make their theories more readily “testable.”

Alfred Marshall’s distrust of “long chains of deduction,” as well as the whole Cambridge impetus toward such short cuts, has contributed a great deal to this breakdown. On the other hand, verbal logic in economic theory has been replaced by mathematics, seemingly more precise and basking in the reflected glory of the physical sciences.

The dominant econometric wing of mathematical economists also looks for empirical verifications and thereby compounds the errors of both methods. Even on the level of pure theoretical integration, mathematics is completely inappropriate for any sciences of human action. Mathematics has, in fact, contributed to the compartmentalization of economics — to specialized monographs featuring a hyperrefined maze of matrices, equations, and geometric diagrams.

But the really important thing is not that nonmathematicians cannot understand them; the crucial point is that mathematics cannot contribute to economic knowledge. In fact, the recent conquest of mathematical economics by econometrics is a sign of recognition that pure mathematical theory in economics is sterile. [All emphasis added]

Rothbard’s entire preface is online at Mises.org. You can also buy the book at Amazon.com here.