The connection between internal and external validity is a matter of some debate in the philosophy of science. Some authors claim that there is a tradeoff between internal and external validity; some argue that internal validity is a pre-requisite for external validity. This paper presents an attempt at resolving the tension between these two views. The main contention is that the two views refer to different components of internal and external validity. The tradeoff is reframed as a tradeoff between the degree of confidence that a researcher can attain about the internal validity of her result and the degree of confidence she can attain regarding its external validity. This interpretation of the tradeoff is compatible with the prerequisite view. An important implication of this reinterpretation is that the tradeoff relationship places a constraint on experimental design, while the prerequisite relation does not.
How to Cite:
Busch, C., 2017. The relationship between internal and external validity. Rerum Causae, 9(2), pp.71–91.