In this piece the author takes issue with Mario Bunge’s claims that conceptual and semiotic systems have "compositions, environments and structures, but no mechanisms." Structures, according to Bunge, can never be mechanisms in conceptual and semiotic systems. Contra this the author argues that in social systems, social structures (which are concept-dependent and reproduced and/or transformed, at least in part, semiotically), can be mechanisms in the sense that such structures are one of the processes in a concrete system that makes itwhat (...) it is. As such, not only may conceptual and semiotic systems have mechanisms, but they may also themselves be considered some of the mechanisms that make the social what it is. As such, they can be said to possess powers and liabilities that neither reside at lower levels nor are explainable in terms of the lower level. To hold out the prospect of social explanation by conceptual and/or semiotic mechanisms does not represent an attempt to decouple these systems from material factors. What it does mean is that conceptual and/or semiotic systems can, potentially at least, play a role in social explanation; and themselves be subject to explanation. Key Words: mechanisms • social • structures • cause • explanation • realism • emergence • reductionism. (shrink)