Case Studies and Theory Development in the Social Sciences - Alexander L. George [117]
Process-tracing is particularly useful at addressing the problem of equifinality by documenting alternative causal paths to the same outcomes and alternative outcomes for the same causal factor. In this way, it can contribute directly to the development of differentiated typological theories. Finally and most generally, process-tracing is the only observational means of moving beyond covariation alone as a source of causal inference. Whether it is pursued through case studies, correlations, experiments, or quasi-experiments, it is an invaluable method that should be included in every researcher’s repertoire. It can contribute in ways that statistical methods can do only with great difficulty, and it is often worthwhile even when sufficient cases exist for the concurrent use of statistical methods. The power of process-tracing for both theory testing and heuristic development of new hypotheses accounts in part for the recent “historical turn” in the social sciences and the renewed interest in path-dependent historical processes.
However, we do not regard the within-case methods such as process-tracing as competitive with case comparisons or statistical analysis; rather, both within-case and cross-case analyses are important for advancing theory testing and theory development. The two methods provide different and complementary bases for causal inference. Case studies are superior at process-tracing, which relates to the causal mechanism component of causal explanation. Statistical studies are better at measuring the observed probability distribution relating measures of an independent variable to measures of outcomes across a large number of cases, which relates to the component of causal explanation defined as causal effects.447 More attention needs to be given to developing ways in which researchers working with each method can complement one another in well-designed research programs, because it is seldom possible for a single researcher to apply both methods with a high level of proficiency. We turn now to a discussion of the logic of historical explanation.
Process-Tracing and Historical Explanation: Similarities and Differences
The question is sometimes asked whether process-tracing is similar to historical explanation and whether process-tracing is anything more than “good historical explanation.” It is not unreasonable to respond to such an observation by asking what is a good historical explanation! We indicated earlier in this chapter how a process-tracing explanation differs from a historical narrative, and emphasized the desirability for certain research purposes of converting a purely historical account that implies or asserts a causal sequence into an analytical explanation couched in theoretical variables that have been identified in the research design. Some historians object that converting a rich historical explanation into an analytical one may lose important characteristics or the “uniqueness” of the case. This is true, and information loss does occur when this is done, and the investigator should be aware of this and consider the implications for his or her study of the fact that some of the richness and uniqueness of the case is thereby lost. But ultimately we justify the practice of converting historical explanations into analytical theoretical ones by emphasizing that the task of the political scientist who engages in historical case studies for theory development is not the same as the task of the historian.
Nonetheless, understanding of