Dr. Mirrlees, who shared the 1996 Nobel Prize with William Vickrey of Columbia University, approached economics from a background in mathematics. He was particularly fascinated by ideas first put forth by Vickrey and others concerning “information asymmetry,” in which one party in an economic transaction is privy to knowledge the other does not have.
“That just means not knowing as much as you would like,” Dr. Mirrlees explained.
He sought to explore the implications of information asymmetry and how it affected individual behavior and economic policy.
A simple example of the concept would be when someone offers a used car for sale. The seller has a greater understanding of the condition of the automobile than the buyer. The idea has been used to understand costs and benefits in real estate, health insurance, investing, welfare and employee motivation.
“My subject has always been economics and human welfare,” Dr. Mirrlees said after winning the Nobel.
He was perhaps best known for his work on “optimal taxation,” for which he developed a mathematical model to define a balance between what he called equity and efficiency. In other words, he sought to find a point where government taxation would provide a shared benefit to society without being an onerous burden on individual workers.
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The happiest day in his life, he said, was not the day he learned that he was to receive the Nobel but another day, in 1968, when he “finally cracked the optimal tax problem. . . . It came in a flash and was very satisfactory.”
Tax codes were traditionally based on income levels, graduated to assess a higher tax rate on people who earned more money. Dr. Mirrlees was interested in discovering whether there was a point of diminishing return, when high taxes would reduce the motivation of productive workers.
“Mirrlees’s work on the optimal income tax was a starting point for a vast amount of research,” economist Bengt Holmstrom of the Massachusetts Institute of Technology told the New York Times in 1996.
His theories were seized on by people across the political spectrum, from those who supported higher taxes to provide increased government services to those who advocated a “flat tax” rate that would be the same at all levels of income.
“Every member of the House Ways and Means Committee and every lobbyist has been practicing Jim Mirrlees’s tax theory for years as they have argued about the efficiency of various tax policies,” former Treasury Secretary Lawrence H. Summers told the Times in 1996. “He provided the first mathematically rigorous treatment of efficiency and equity that is central to modern economic policy debate.”
But his statements on economic policy were open to interpretation. He suggested that the highest tax rates in Britain — which exceeded 80 percent when he developed his theories — could cause top earners to grow discouraged and stop working hard.
On the other hand, he said taxes “could reasonably be higher, particularly for middle income earners” and could easily exceed 50 percent without affecting productivity.
“It could become a disincentive,” he said, “but you could use the revenue for health services, education, and welfare payments.”
His private views, he said in 1996, were in line with Britain’s liberal Labour Party “because of a desire for egalitarianism, not for any great fondness for public ownership.”
James Alexander Mirrlees was born July 5, 1936, in Minnigaff, Scotland. His father worked in banking, and his mother was a homemaker.
He studied mathematics at Scotland’s University of Edinburgh, graduating in 1957, then enrolled at the University of Cambridge in England, obtaining degrees in mathematics and economics before receiving his doctorate in economics in 1963.
He joined the Oxford faculty in 1968 and was considered an inspired teacher. He had interim appointments at MIT, Yale University and the University of California at Berkeley. He advised Asian and African governments on economic policy before returning to Cambridge in 1995. He later had a faculty appointment at the Chinese University of Hong Kong.
His wife of 32 years, Gillian Hughes, died in 1993. Survivors include his wife since 2001, the former Patricia Wilson; two daughters from his first marriage; a stepson; and four grandchildren.
Dr. Mirrlees had a reserved nature and enjoyed spending his free time playing the piano and reading detective novels. He had a sunny confidence in the economy and in the ability of people to adapt to changing times.
“People will get employed doing other things,” he said. “That is the faith of economists, which non-economists find hard to believe: There will be other jobs somewhere else.”
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