We focus on the debate on the external validity of lab results in the area of experimental economics. More specifically, we focus on Colin Camerer’s and John List’s views, who postulate opposite positions on the issue. The problem is that they partially analyze the same empirical evidence and draw from it opposite conclusions. The goal of this work is to analyze such empirical evidence to try to explain the difference in interpretation of results. We argue that the dispute in interpretations (...) can be expressed in terms of difference of criteria used to determine external validity. From our analysis we propose the formulation of different types of external validity. (shrink)