 Economists Thorstein Veblen, John Maynard Keynes, Herbert A. Simon, and many of the Austrian School criticise "homo economicus" as an actor with too great an understanding of macroeconomics and economic forecasting in his decision making.They stress uncertainty and bounded rationality in the making of economic decisions, rather than relying on the rational man who is fully informed of all circumstances impinging on his decisions.They argue that perfect knowledge never exists, which means that all economic activity implies risk.