The economist who believed that unemployment is impossible and that market mechanism has a built in regulatory system to meet any ups and downs - (1) J.M.Keynes (2) Ohlin (3) J. B. Say (4) Galbraith
(3) J. B. Say Explanation: The classical economists' belief in full employment as a normal condition of a free market economy is based on Say's Law of Markets. It was on the basis of this law that the classical economists thought that general overproduction and hence general unemployment were impossible. The law simply states "supply creates its own demand."