A key debate in the study on land, housing and natural resources revolves around the notion that general institutional forms (such as private, common, public, and likewise formal property rights) lead to a certain institutional performance (as may be expressed in terms of prices, transaction costs or sustainability). However, a modest, yet, growing stream in institutional analysis aims to move away from 'merely describing the characteristics' of institutions (i.e., form variables) to 'performance or quality measures' (i.e., function variables). Following this line of argument, the credibility thesis as put forward in this journal (Ho, 2014) postulates that the form of institutions is unrelated to their performance, and institutions are unintentional outcomes rather than designed artefacts. The primary goal of this research is to ascertain whether this dual prediction could be observed in a simulation model that is driven by agent behaviour and interaction, resulting in emerging institutions. We devise an empirically verified agent-based model within a classical thought experiment on a common property resource to validate the thesis' predictions. First, our model confirms that different forms of institutions can have a similar performance. Second, we ascertain that successful institutions in difficult management situations can emerge (rather than being designed) that are beneficial for the sustainability of the common resource and the appropriators of that resource.