The first American Nobel laureate in economics, Paul A. Samuelson, died Sunday at his home in Belmont, Massachusetts, at the age of 94. Samuelson was the foremost academic economist of the 20th century and was instrumental in making the Massachusetts Institute of Technology into one of the great centers for graduate education in economics by bringing scores of brilliant thinkers to the school. He won his Nobel in 1970, and was recognized for moving the discipline from being concerned mostly with abstract questions into one that solves problems with mathematical clarity. Samuelson gave a 40-minute lesson to John F. Kennedy after he won the 1960 presidential election, and advised him throughout his presidency. But he refused to be Kennedy’s pick to chair the Council of Economic Advisers, because he did not want to have to censor his writing.