Who was the first economist, who challenged the classical theory
Answers
Classical economics or classical political economy is a school of thought in economics that flourished, primarily in Britain, in the late 18th and early-to-mid 19th century. Its main thinkers are held to be Adam Smith, Jean-Baptiste Say, David Ricardo, Thomas Robert Malthus, and John Stuart Mill. These economists produced a theory of market economies as largely self-regulating systems, governed by natural laws of production and exchange (famously captured by Adam Smith's metaphor of the invisible hand).
John Maynard Keynes thought of classical economics as starting with Ricardo and being ended by the publication of his own General Theory of Employment Interest and Money. The defining criterion of classical economics, on this view, is Say's law which is disputed by Keynesian economics.