He introduced the "liquidity trap" featured in his neo-Keynesian work Mr. Keynes and the Classics.  
He introduced the "liquidity trap" featured in his neo-Keynesian work Mr. Keynes and the Classics.  He attempted a restatement of the marginal productivity theory in his 1932 Theory of Wages and coined the term "elasticity of substitution."  In a paper with R. G. D. Allen, he introduced the Slutsky decomposition of demand into substitution and income effects and developed the IS-LM model, but he is better known for his Value and Capital, in which he established the foundations for general equilibrium theory.  FTP, identify this economist that shared the 1972 economics Nobel with Kenneth Arrow.
He introduced the "liquidity trap" featured in his neo-Keynesian work Mr. Keynes and the Classics.  
Sir John Hicks