Robert Dahl, a force in the field of political science, died yesterday at the age of 98.

A Sterling professor emeritus of political science at Yale, Dahl’s work included writings on democracy, foreign policy, the United States Congress, welfare, the United States Constitution and other topics. In 1985, Foreign Affairs called him the “dean of American political scientists.”

Dah’s work spanned more than six decades of political thought. After receiving his doctorate from the University in 1940, he went on to play a major role in shaping Yale’s modern political science departments during the 1950s and 1960s.

His work spanned more than six decades of political thought. After receiving his doctorate from Yale’s newly created government department in 1940, he spent six years working in Washington and serving during World War II. Upon returning to Yale after the war, Dahl engaged in a nascent discipline — political science — pioneering the use of empirical techniques in the study of politics.

Dahl was also a member of the National Academy of Sciences, the American Philosophical Society and the American Academy of Arts and Sciences.