Hawley's risk bearing theory of profit from 1893 states that profit is the reward entrepreneurs receive for taking risks in business. Higher risks taken on by entrepreneurs lead to greater potential profits. There are four main types of risks according to Hawley: replacement risk, risk proper due to time lags between production and sale, uncertainty about possible outcomes, and obsolescence risks from new technologies. While critics acknowledge entrepreneurs bear some risks, they argue risks are not the sole determinant of profits, and entrepreneurs provide additional functions like coordination and supervision beyond only risk taking.