In Glenn Loury’s memoir, Late Admissions, the author states that he was the first to coin the term social capital as a retained value obtained through contact with social groups and activities. It appears in the following paper.
An individual’s social origin has an obvious and important effect on the amount of resources which are ultimately invested in his development. It may thus be useful to employ a concept of “social capital” to represent the consequences of social position in facilitating individual acquisition of (say) the standard human capital characteristics. While measurement problems abound, this idea does have the advantage of forcing the analyst to consider the extent to which individual earnings are accounted for by social forces outside the individual’s control. However, for precisely this reason such analysis is unlikely to develop within the confines of traditional neoclassical theory. A Dynamic Theory of Racial Income Differences (1976)

In the following decade, James S Coleman, a sociologist at the University of Chicago, writes the paper Social Capital in the Creation of Human Capital (1988). Here, the sense of the term is similar as there is a measurement of the efforts of a father put forth in the education of his son.
But in the 1990s, something changed. Putnam makes social capital a coffee table word in Bowling Alone (1995 article, 2000 book). Now, the term is morphing into a sense of access to networks. The thought is that business, or economic activity, is embedded in social life but clearly separate. Social life is a thing on the side. Benefits from social interactions arrive like electric pulses moving sporadically across a net of human connections.
Thanks to the book’s popularity, everyone grabbed hold of the term social capital from 2000 to 2010. It lost depth as it had become a marketing cliche. At about the same time, Nan Lin published Social Capital: A Theory of Social Structure in Action (1997), advancing the network theory of capital amongst relations.
Social Capital explains the importance of using social connections and social relations in achieving goals. Social capital, or resources accessed through such connections and relations, is critical (along with human capital, or what a person or organization actually possesses) in achieving goals for individuals, social groups, organizations, and communities. The book introduces a theory that forcefully argues and shows why “it is who you know,” as well as “what you know” that makes a difference in life and society.
Attempts are made to measure strong ties and weak ties, and distances between connections, but nothing really comes of it as a measurable model.
Was Glenn Loury thirty years too early with his concept of social capital? Did he bail on the theoretical world of economics too soon?