Process-tracing the Effects of Ideas

This chapter examines the uses of process tracing for empirically testing ideational explanations and theories of political decision making.1 Ideational mechanisms have characteristics that make them especially difficult to study, as compared to materially driven causal processes. Ideas are unusually difficult to measure and are often highly correlated with other plausible causes of political outcomes. Moreover, key mechanisms of ideational influence operate within a “black box ” of unobservability from the perspective of the historical researcher. These challenges of ideational analysis motivate this chapter’s arguments in two respects. On one level, the chapter seeks to demonstrate that process-tracing represents an especially powerful empirical approach for distinguishing between ideational and material effects. At the same time, the chapter reckons with the considerable challenges that the study of ideational causation presents, even for careful process tracing. The chapter offers ideational analysts a set of process-tracing strategies as well as guidance in identifying the conditions under which each strategy can be fruitfully applied. Broadly, the paper emphasizes three hallmarks of effective tracing of ideationa