“You have the vote of every thinking person,” a woman assured Adlai E. Stevenson during one of his presidential campaigns. To which Stevenson, so the story goes, replied skeptically: “That’s not enough madam — we need a majority!”

According to Philip E. Converse, Stevenson’s skepticism was well founded. In 1960, after Stevenson had been defeated twice by Dwight D. Eisenhower, Professor Converse, then a 32-year-old research scientist at the University of Michigan, concluded with three co-authors that most American voters were remarkably uninformed and nonideological, and that they based their preferences largely on party affiliation.

Since then, many political scientists have tempered that view, given the flood of information available to voters from television and other new technology and the general attenuation of partisan ties. Still, the original research on “The American Voter,” with Angus Campbell, Warren Miller and Donald Stokes, and Professor Converse’s elaboration in a 1964 article, “The Nature of Belief Systems in Mass Publics” in “Ideology and Discontent,” began a continuing debate over what part a candidate’s character, party affiliation, policy positions or overall ideology play in voters’ minds.

It created what Nancy Burns, a political scientist at the University of Michigan, called “the architecture of our understanding of public opinion.”

Professor Converse, a professor emeritus of sociology and political science at Michigan, died at 86 on Dec. 30 in Ann Arbor....