Agent-based modeling is a promising new route in macroeconomics research. Questions have been raised, however, regarding the validity of such models. A deeper understanding of the validation methodology in MABM is required. In order to provide this, I connect three frameworks. The first framework regards the foundations of model validation in general. In this framework, I will give a definition of model validation and relate this to the concept of model domain. The second framework regards a classification of models, dependent on how a model is validated. An important distinction in the framework is the difference between mechanism and target validation. The third framework revolves around the relationship between the structure of models of complex systems with emergent properties and validation in practice. Important in this framework is to consider MABMs as modeling multiple non-trivial levels that are subject to distinct forms of validation. By connecting these three frameworks, I will come to several conclusions regarding how we should characterize MABMs. First, it is important to pinpoint what the mechanisms of MABMs are constituted by. I will argue that the mechanisms at a lower level are distinct from, but provide input to, higher levels of mechanisms. Since mechanisms at different levels are validated in different ways, I come to a specific characterization of MABMs within the model classification framework, that is, in some ways, distinct from other types of models in macroeconomics. Second, I will show that because the mechanisms of MABMs are validated in a direct way at the level of the agent, MABMs can be seen as a move towards a more realist approach to modeling compared to the neoclassical approach.
