The British philosopher, John Stuart Mill, suggested two approaches to learning about “what works” in the real world: 1) forward causal questioning by studying “effects of causes” and 2) reverse causal investigation by studying “causes of effects.” Tracking and learning from both approaches to learning about “what works” should be prioritized in international development.
Forward causal questioning—or studying “effects of causes”—involves asking questions such as, “What health and education related results for children can be achieved by implementing a set of interventions in a community?” In other words, what results (i.e., effects) for children will be achieved from by certain interventions (i.e., causes)? This is the most common approach to learning “what works” in international development. Historically, various types of prospective evaluation (ex ante) methods have been used by international development organizations to answer forward causal questions, which include results monitoring using baseline and end-line studies, participatory evaluation, developmental evaluation, and experimental and quasi-experimental designs to mention a few. The purpose of studying “effects of causes” is fundamentally to validate the program’s Theory of Change (ToC): that is, how its program’s strategies and interventions produce intended results and impacts. Advantages of prospective evaluation approaches include 1) being able to track program effectiveness during implementation for needed improvements if necessary, 2) accountability to beneficiaries and donors during the program cycle and at its closure, and 3) assessing to what degree intended results were achieved. However, the limitations of forward causal questioning are that it does not account for 1) the possibility of omitted or unobserved causal mechanisms in the program’s ToC, 2) that programming sensibly changes and evolves which is not often captured by pre-designed evaluation systems, and 3) longer-term impacts, both positive and negative, that may appear years after program closure are unknown and undocumented. However, international development organizations can overcome many of these limitations to learning, inherent in forward causal questioning, by use of what Mill’s second approach: reverse causal investigation.
Reverse causal investigation involves learning about “what works” by studying “causes of effects.” That is, systematically following the causal chain backward in time and seeking to account for more and more causes that help explain an observed result(s) or impact(s). Using the health example above, reverse causal investigation asks, “What were the causes of currently observed child-related health and education results in a community?” In other words, what are the program and non-program factors (causes) of the observed results for children (effects)? Reverse causal investigation involves the use of a retrospective evaluation (ex post) approach that involves the use of methods and techniques such as process tracing, contribution analysis, causal chain analysis, ripple effect mapping, large data mining, and systems mapping to mention a few. Advantages of retrospective approaches are that they can 1) provide the opportunity to explore and identify unexpected causes not in the program’s ToC, both major and minor, that may revise or challenge outright the program’s ToC, 2) identify certain causes that may be more instrumental in sustainability of the program’s expected results, 3) investigate if the program’s intended results became causes of additional positive (that underestimate impact of program) or negative results, 4) seek and understand unintended (wayward) outcomes, 5) examine which interventions work for whom, and how, in a particular context, and 6) avoid the political pressure to provide immediate, performance results as with prospective evaluations. But, disadvantages of a retrospective approach include the need for additional funding beyond the life of the program and the challenge of disentangling the increasingly confounding influences that enter the causal chain the longer a retrospective study is delayed.
Undeniably, forward causal questions or prospective evaluation of “effects of causes “dominates learning about “what works” in international development rather than reverse reasoning or retrospective evaluation of “causes of effects.” Since prospective evaluation approaches are most often part of a program’s budget, due to the requirement to monitoring progress of the interventions toward achieving results for accountability, this dominance is understandable. Moreover, using scare resources for costly prospective approaches, such as experimental and quasi-experimental designs in the search of sole attribution as the standard for determining “what works,” inhibits the use of reverse causal reasoning and retrospective evaluations.
In the future, international development organizations and donors should continue with forward causal questioning that leads to learning from immediate development programming experiences but should also prioritize reverse causal reasoning that leads to learning from reflection and broader investigation of a holistic causal chain involved in a development program’s outcomes. Retrospective approaches can provide key insights into “from beginning to end” processes that are inaccessible with prospective approaches. The mathematician, Morris Kline, summarizes why the inclusion of reverse causal investigation for learning is essential: “The most fertile source of insight is hindsight.” Only by studying both “effects of causes” and “causes of effects” will it be possible to better understand the complex set of necessary and sufficient causes to produce sustainable program results and impacts and, ultimately, “what works.”