  William Stanley Jevons (1835–1882) was an economist and philosopher who foreshadowed several developments of the 20th century. He is one of the main contributors to the ‘marginal revolution’, which revolutionised economic theory and shifted classical to neoclassical economics.  He was the first economist to construct index numbers, and he had a tremendous influence on the development of empirical methods and the use of statistics and econometrics in the social sciences.  His philosophy can be seen as a precursor of logical empiricism, but because of the peculiar form of his logic, he would not have many direct followers.  His textbooks on logic were widely used in class and reprinted many times. 