The implementation of keynesian countercyclical measures is criticized by neoclassical (new classical) economists who developed ..

Public Choice Theory

Explanation:

Both classical economists who developed PUBLIC CHOICE THEORY and free-market advocates have criticized Keynes' approach. These two schools of thought argue that the market is self-regulating and businesses responding to economic incentives will inevitably return it to a state of equilibrium. On the other hand, Keynes, who was writing while the world was mired in a period of deep economic depression, was not as optimistic about the natural equilibrium of the market. He believed the government was in a better position than market forces when it came to creating a robust economy.

explanation:

may i ask what challenges?