Jack Walker was the author of three of the 100 most cited articles in the history of the Review.¹

Nowhere is his creativity and imagination more on display than in his “Diffusion” article. Comparing the three articles allows some conclusions about why “Diffusion” had such a great impact and illustrates the thinking of a great scholar, mentor, and colleague.

Jack was a contributor to many fields. After I invited Jack to give a lecture some years ago, a colleague stopped me to say how glad he was that a theorist was visiting. Another thanked me for inviting a state politics expert; a third was thrilled to have an interest-group scholar; and a fourth, an agenda-setting pioneer. Jack's first big splash in the profession came when he was just two years into the tenure track, when he took on some of the biggest establishment figures in the discipline with his provocative “Critique of the Elitist Theory.” It was combative, addressed major issues of power, and was perfectly timed to coincide with the rise of a new, more critical form of pluralist analysis. (Graduate students take note: it was also a revision of an essay he had drafted for his qualifying exams.) His second major contribution was “Diffusion,” also written as an assistant professor. His third major article, “Origins and Maintenance,” took aim at a major theme in the literature on group mobilization, suggesting important ways that elite-level actors, including the state itself, affect social mobilization. The continuing upward slope in citations to “Diffusion” and “Origins” make clear that these articles still attract significant attention even decades after their original publication.

As influential as “Critique” and “Origins” have been, “Diffusion” is clearly in a different class. What makes this so? Unlike the other two articles, “Diffusion” is neither critical nor combative. Rather, it launched an entirely new field of research. Like both “Critique” and “Origins,” but to an even greater extent, “Diffusion” has attracted considerable attention outside of political science. Indeed, more than four of every ten citations of it have been from other disciplines, including sociology, economics, health, law, education, business, geography, and several others—20 in all, by my count.

Overseeing an internship program in Lansing when he was an assistant professor, Jack noted that lawmakers often asked agency officials whether other states provided precedents for programs under review (Interview with Jack Walker). He was struck by the rise of national professional communities, experts who had intense communications within networks of expertise rather than within the local political environment. This concern with “knowledge communities” informed his later work on lobbying as well. It typifies his approach to political science, for he took an idea that had barely been noticed by others but was there for all to see. It had wide-ranging applicability and implications, as the subsequent literature demonstrated. The work has been cited in 20 different disciplines, and it is almost as widely used outside of political science as within our discipline. Within political science, the article led to some controversy and methodological critique (something Jack never minded!), and generated an entire new field of research that remains vibrant today (in fact, three other articles on diffusion, by Mohr, Gray, and Berry and Berry, are on the Review's 100+ list). Not everyone who has cited “Diffusion” has read it carefully; as the first cite in its field, it appears often to be used as a simple reference to justify an assumption that diffusions do, in fact, spread rapidly. In fact, Jack was just as interested in those innovations that did not diffuse and in those states that were proud to be laggards.

One sign of Jack's creativity comes from remembering that all this stemmed from a department head's assignment to supervise an internship program in the state capital. With nothing else to do between meetings, he developed an entirely new research paradigm. The list of scholars having published three articles in the list of top Review citation-getters includes such luminaries as Warren Miller, Donald Stokes, Ronald Inglehart, Phillip Converse, and others. No one appears on this list four times. If Jack had not been killed in a car accident sixteen years ago, in the prime of his career, he may well have broken that tie.