James Tobin
James Tobin (March 5, 1918 – March 11, 2002) was an American economist who served on the Council of Economic Advisers and the Board of Governors of the Federal Reserve System, and taught at Harvard and Yale Universities. He developed the ideas of Keynesian economics, and advocated government intervention to stabilize output and avoid recessions. His academic work included pioneering contributions to the study of investment, monetary and fiscal policy and financial markets. He also proposed an econometric model for censored endogenous variables, the well-known "Tobit model". Tobin received the Nobel Memorial Prize in Economic Sciences in 1981.
Tobin tax
Keynes' concept stems from 1936 when he proposed that a transaction tax should be levied on dealings on Wall Street, where he argued that excessive speculation by uninformed financial traders increased volatility. For Keynes (who was himself a speculator) the key issue was the proportion of 'speculators' in the market, and his concern that, if left unchecked, these types of players would become too dominant.