JAMES Q. WILSON, who died last week at the age of 80, was unquestionably the pre-eminent political scientist of the last 50 years. Curiously, the commentary surrounding his death has largely focused on his justly famous “broken windows” theory — and to a lesser extent, his penetrating 1993 book, “The Moral Sense” — yet these works are only a small part of his extraordinary contribution to sound thinking about government, politics and public policy.

In two early books, Mr. Wilson deployed this theory, along with intensive fieldwork, to show how such incentives help explain — and predict — the behavior of diverse political organizations. In his 1960 book, “Negro Politics,” he compared two diverse styles of politics of the most prominent black congressmen of the day, William Dawson and Adam Clayton Powell Jr.

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Two years later, in “The Amateur Democrat,” Mr. Wilson compared the disparate organizational strategies of Democratic political clubs in Los Angeles, New York and Chicago. The Chicago clubs were essentially cogs in Mayor Daley’s materialistic machine. The New York clubs were divided between organizational regulars and insurgent reformers — groups driven (and riven) by different incentive systems in a city whose politics, unlike Chicago’s, could not centralize power enough to control policy outcomes.

The political style of the Los Angeles clubs was the most striking, as it prefigured a new kind of politics that has largely defined the Democratic Party ever since: it elevated the intra-party influence of “amateurs” over professional politicians, demanded ethnic and gender balance in internal party affairs, mistrusted central leadership and (until recently) avoided broad coalition building with business interests. This more ideological, protest-type mode (so evident in today’s Republican Party as well) made it very difficult for them to unify and aggregate the power needed to govern effectively in a decentralized political system like ours.