Two Types of Formal Generative Mechanisms
Outwardly the two formal types look the same. Each has two parts, a small first part containing the premise(s) or assumption(s) and a large and growing second part containing deduced implications.
But inwardly they differ. In Type 1, the assumptions are known to be true, they may even be self-evident; or the assumptions may describe a set of arrangements under human or institutional control. Thus, the implications must be true. In Type 2, the assumptions are what Popper (1963:245) called "guesses" about the way the world works. The implications are testable, falsifiable predictions. If the predictions survive rigorous empirical test, such tests constitute evidence that the real world may resemble the world postulated in the guesses.
Thus, although the deductive apparatus is the same in both types, the two types have different properties and operate differently. Importantly, they lead to different empirical questions and tasks. In the Type 1 mechanism, the empirical task is to assess the conditions under which the assumption holds; deduction tells us that if the assumption holds, then the deduced implications must be true. On the other hand, in the Type 2 mechanism, the empirical task is to assess the validity of the predictions; the empirical status of the predictions tells us whether the assumptions are a faithful representation of the real world.
For concreteness, the paper provides an illustration of each of the two types, drawn from the status model (Sørensen 1979) and the wage-setter model (Jasso 2009). Close examination of the two illustrations increases our understanding of the two types of mechanisms, as well as of the embedded causal relations.