For more than 40 years Nelson Polsby was a leading figure in American political science. For seven years he was editor of the subject’s premier journal, the American Political Science Review, and his friendships and books and articles on US political parties, elections, Congress and the media made him a mentor to generations of graduate students.

Naturally warm and gregarious — if also at times cantankerous — he helped to build strong communities, at his beloved University of California, Berkeley (UCB), at its Institute of Government Studies (IGS), which he headed for ten years, and in the wider political science profession. An Anglo-phile, from his years at the London School of Economics and as Olin Professor of American Government at Oxford, he had many friends in Britain.

Nelson Woolf Polsby, born in 1934, came from Yankee Jewish farming stock, based in Con-necticut. His family encouraged his precocious interest in current affairs. In the early 1900s a great-uncle ran for the mayoralty in New Haven as a socialist.

His father, a successful businessman, died after a surgical mishap when Nelson was 11. At prep school (there were not many Jewish farm boys, and even fewer at prep school) he was a brilliant student, turning down offers from Yale and Harvard universities to attend Johns Hopkins. This enabled him to sit in the Senate galleries and observe that institution at work.

His academic breakthrough came from his association with Robert Dahl’s pathbreaking study of political power in New Haven in the 1950s, Who Gov-erns? (1961). His doctorate was published as Community Power and Political Theoryin 1963 and was quickly regarded as a masterpiece. He argued that rather than a single dominant elite running things, there were different elites in different areas and that this pluralism was compatible with democracy.

Polsby spent six years at Wesleyan University, becoming a full professor in 1967. That year he moved to UCB, where he remained for the rest of his career, in spite of offers from other universities, including Yale and Harvard. At an early stage, therefore, he had developed his two chief interests; the theory of democracy and how it operates in practice.

He also developed his lifelong interest in Congress, particularly the House of Representatives, in the 1960s. He showed how it had become institutionalised and how the seniority system for allocating key roles developed. He also analysed how the large contingent of Democrats (“Dixie-crats”) from the segregationist and more conservative South, in contrast to the more liberal Democrats from the North, prevented that party using its nominal majority to give effective leadership to Congress. Later, in How Congress Evolves (2004), he explored the decline of the South in the House and the emergence of sharper partisanship in its operations.

In 1964 he and his dynamic UCB colleague, Aaron Wildavsky, published Presidential Elections. Revised and published quadrennially — its 11th edition was in 2004 — it remains the standard text on the topic. After Wildavsky died in 1993, Polsby was the sole author and claimed that: “The only difference since Aaron’s death is that I win the arguments.” His prose was highly readable and marked by wide reading and incisive analysis. He was ambitious and worked very hard to maintain his reputation and keep up with UCB colleagues; he confessed that his insomnia was caused by noticing that the lights in the rooms of colleagues in the early hours of the morning — they were still at work! He quipped: “While Polsby sleeps, Wildavsky publishes.”

He also wrote witty pieces on politics under an assumed name, Arthur Clun (borrowed from Angus Wilson’s Anglo-Saxon Attitudes). They prompted a publisher to offer a book contract to the mystery author. A keen observer of the British political scene, he collaborated with Geoffrey Smith, a political commentator on The Times, to publish British Government and its Discontents in 1981.

At 37 he received the accolade of the editorship of the APSR.For six years he successfully managed, in a relaxed style, a large staff and coped with pressures from authors and reviewers.

Polsby was a popular choice to become director of the IGS in 1988. He seemed to know everybody and to have read almost everything. He invited visiting scholars and politicians to talk about their work and their experiences — his good friend, Chris Patten was a regular visitor. He did much to create a friendly atmosphere, and a high point was the afternoon tea at which he presided. But he was less successful as a fundraiser because he could be overbearingly opinionated when faced with the deeply held views of potential donors.

Having basked in the acclamation for his work he was desolate when his term expired in 1999, a consequence of the university’s ten-year rule for tenure. The institute had meant so much to him.

His Consequences of Party Reform (1983) was sharply critical of some of the effects of the reforms the Democratic Party made to the presidential nominating process in the late 1960s. These gave increased representation to some minorities (race and gender) but not others, and increased the influence of single-issue groups in the party’s deliberations. But they also weakened the party’s ability to nominate presidential candidates representative of the broad American public and to win elections. Polsby was always concerned about good government and citizenship.

Polsby had a dominating physical presence; a mountain of a man, he looked like an American footballer gone to seed. Dressed in a T-shirt and corduroys, he shuffled rather than walked and breathed heavily, and friends constantly worried over his health (he had a number of angioplasties). But the flow of epigrams, witticisms, attacks on the higher nonsense of political science, and stimulating ideas continued. He was constantly judg-mental about other politicians and academics. But if he argued with someone it was a mark of his approbation. Speakers who assumed that Polsby, eyes shut and snoring in the audience, was asleep could quickly be confounded when the “sleeper” made a pertinent, or ferocious, intervention.

He received many honours, including honorary degrees from the universities of Liver-pool and Oxford. He had the respect of political reporters, and many politicians, for his understanding of the constraints under which they worked, and he drew readily on his encyclo-paedic knowledge of US politics to provide wise counsel. He regarded his frequent contributions to “round tables” and oped pages as part of a professional obligation to inform the public, entertaining “the delusion that too few of my opinions were available to the world at large”.

At home, Polsby and his wife Linda provided rich hospitality for their many Berkeley and overseas friends. Both loved food — in spite of constant diets — and for a time they jointly wrote a column on restaurants for Californiamagazine. He was a keen follower of the local Oak-land Athletics baseball team. But most of all he loved passionate argument with friends.

Polsby is survived by his wife, Linda, and by their two daughters and son.

Professor Nelson W. Polsby, political scientist, was born on October 25, 1934. He died of heart trouble on February 6, 2007, aged 72