ABSTRACT
A mechanism is the way a process precedes. The original concept of a mechanism has been considerably broadened since the seventeenth century, when natural science was dominated by mechanics. There are mechanisms of many kinds: electromagnetic, nuclear, chemical, cellular, intercellular, ecological, economic, political, and so on. Tilly analyzes and inter-relates four mechanisms that cause and maintain social inequality, which he calls exploitation, opportunity hoarding, emulation, and adaptation. Mechanismic explanation differs not only from mere subsumption but also from the "comprehensive" or "interpretive" account favored by the hermeneutic or Verstehen school. A physiological mechanism is a collection of processes inside an organism, and a political mechanism—such as popular mobilization in favor or against a proposed bill—is a collection of processes inside a polity or among polities. A description of a process, without any reference to the underlying mechanism, may be said to be kinematical. Kinematical accounts are devoid of explanatory power.
