This paper analyzes the theory of “entrepreneurial incentives” in the work of Israel Kirzner. It argues that there is a logical problem with the notion of profit opportunities as exogenous causal agents: Without additional assumptions, the existence of opportunities alone does not sufficiently explain the alertness of entrepreneurs. The paper considers both stronger and weaker versions of this problem. It also questions the relation between entrepreneurial incentives and the tendency toward entrepreneurial success. Finally, it provides some commentary on the relevance of entrepreneurial incentives for an overall theory of the entrepreneur, and identifies several potential solutions to the problems discussed.