[Jerry Z. Muller is a professor of history at the Catholic University of America, Washington, D.C., and author, most recently, of "Capitalism and the Jews" (Princeton University Press).]

In recent decades, economists have been struggling to make use of the concept of human capital, often defined as the abilities, skills, knowledge and dispositions that make for economic success. Yet those who use the term often assume that to conceptualize a phenomenon is a first step to manipulating it. And, indeed, "human-capital policy" is now much in fashion. But what if many of the abilities and dispositions in question are a product of history, capable of being understood and explained but not readily replicated?

Simon Kuznets, one of the 20th century's great economists, was a pioneer of human-capital theory. Not long before he died, Kuznets recommended to a young colleague that one ought study the role of Jews in economic life.

By and large, economists and other social scientists have neglected the history of Jews and capitalism, for reasons that are understandable, though unconvincing. For most economists, the extent to which modern capitalism has been shaped by earlier cultural predispositions is a source of puzzlement at best, if not merely a factor to be dismissed....

A look at the historical experience of the Jews shows that while most Jews were mired in poverty at the beginning of the 20th century, over time they tended to do disproportionately well in societies that allowed them to compete on an equal basis. That was the case first in central and western Europe and then in the United States....

There are a number of ways to account for Jews' disproportionate achievement. For one thing, Jews had more experience with commerce than most other groups and the tacit knowledge of buying, selling and calculating advantage that was passed on in families with ties to business helps explain why Jews tended to be better at it.

Moreover, in much of Europe, Jews had long been excluded from most of the established economy of land ownership and from many other fields that were reserved for Christians. So they learned to be on the lookout for new opportunities in underserved markets, working as peddlers, for example, or creating new products, or new forms of marketing.

Social networks also played an important role. Jews were spread across many countries, but to some extent shared a common language and a sense of common fate. So they were more aware of distant opportunities, had more international contacts and were disproportionately active in international trade.

In addition, Jews had a religious culture that promoted universal adult literacy - at least for men - and a culture that respected book learning. Those attitudes and dispositions were transferred from religious texts to secular forms of education. As a result, Jews were highly oriented toward education and willing to defer current pleasures and income to obtain more of it....

But cultures that tend to resent the economically successful - either as an affront to equality, or on the implicit assumption that the economic gains of some must be at the expense of others - tend to be more hostile toward Jews and given to conspiratorial theories to explain their economic success. Most societies lie somewhere along a spectrum between these two poles.

Some social scientists are wary of calling attention to the reality of disproportionate Jewish economic success for fear of arousing anti-Semitism, or contributing to conspiratorial theories about Jewish economic dominance. No doubt, conspiratorial minds will always find fodder for their obsessions. But the fact that the history of Jews and capitalism calls current social-scientific wisdom and method into question is all the more reason to explore the topic.