Austrian capital theory tried to capture the intuitive and basically undeniable importance that time plays in economic life, but arguably was diverted down a blind alley with Eugen von Böhm-Bawerk’s average period of production, a purely physical measure of ‘roundaboutness’—the length of the production process. For the general case, such a measure is a chimera. But the intuition is strong, and the idea survived and reappeared at various points in the history of capital theory. Almost unknown to economists, an alternative value measure of roundaboutness has existed at least since John Hicks’s formulation of his average period (AP) in 1939, which, coincidentally, was exactly the same measure discovered by the financial actuary Frederick Macaulay in 1938, called by him “Duration” (D). Macaulay’s D, more richly interpreted as Hicks’s AP, is a measure that more appropriately captures what it was that the Austrians struggled to express over many years in their capital theory and in their analysis of the business cycle.

Ludwig von Mises seems to be something of an outlier within the Austrian school when it comes to capital – though his position is clearly foreshadowed in a neglected article by Carl Menger (1888). In this paper, we examine Mises's view on capital and suggest that it constitutes a bridge between Austrian and institutional economics. As an outflow of Mises's approach, an incipient financial approach may be discerned, an approach to capital that integrates concepts from financial theory into a broader view of capital that contains both institutional and Austrian elements.

We argue that Fritz Machlup’s (1995) interpretation of Mises’s epistemology is at least as, if not more, plausible than Murray N. Rothbard’s (1957) interpretation. The implications of Machlup’s interpretation of Mises and of Austrian epistemology affect Austrians and non-Austrians in their academic interaction. Machlup’s interpretation shows that Austrian epistemology is well grounded in post-Popperian epistemology and that most criticisms of Austrian economics based on its aprioristic character are misplaced. Furthermore, Machlup’s interpretation provides us with a setting to rebuild the academic interaction between Austrians and non-Austrians that was characteristic of the early twentieth century.