Abstract

According to a classical work on experimental design internal validity “refers to the approximate validity with which we infer that a relationship between two variables is causal or that the absence of a relationship implies the absence of cause”. External validity “refers to the approximate validity with which we can infer that the presumed causal relationship can be generalized to and across alternate measures of the cause and effect and across different types of persons, settings, and times”. Since then, these have been the accepted definitions, with slight variations, of both concepts. However, there have been deep differences in interpreting the scope and limits of validity concepts in economics. From theory-driven experimental designs that defend the priority of the internal over the external validity to those researches that are demanding the importance of external validity in economics, we can find the most diverse points of view. What can experimental ethics learn, then, from recent debates on external and internal validity in experimental economics? If we want to elicit moral intuitions into the lab, are we testing moral theories that way? Could intuitions be generalized “across different types of persons, settings, and times”? Is that really possible?