Policy Mechanisms

  • Adam M. WellsteadEmail author
  • Paul Cairney
  • Kathryn Oliver
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-31816-5_3377-1



Causal mechanisms are an explanatory rather than predictive tool used to unpack the “black boxes” defined by empirical generalizations common in policy research. Specifically, mechanisms can be frequently occurring and easily recognizable causal patterns that are triggered under generally unknown conditions and usually with indeterminate consequences. This approach is appropriate for public administration, public policy, and governance research because it is often based on small N between-case and within-case studies. In testing hypotheses associated with causal mechanism, process-tracing methods are often used.


Issues of causality are infrequently discussed within the public policy and public management disciplines. Positivism and interpretivism are the two most popular approaches. The underlying notion of causality underpinning positivism is one of simple event regularities; that is, there are constant conjunctions of empirically observable, measurable, and predicable events. In contrast, interpretivism is based on the idea that reality is subjective and socially constructed. This view of the social world is constituted by human meaning and sees the main task of research as exploring and understanding subjective human viewpoints. Here, the importance of causality is minimized because all explanations are merely personal or group viewpoints and have to be judged.

However, both of the approaches can be limited for policy researchers who are interested in explaining phenomena such as the policy process because they are often “black boxed.” The causal mechanism approach has become a popular third perspective used to identify the specific details about the cause-and-effect relationships between policy-maker attention to policy problems and their receptivity to policy solutions. When the nature of the mechanism is understood, then it becomes possible to apply rigorous methods and make inferences.

Thinking Mechanistically

There is large “mechanisms” literature, which is influenced by the natural sciences and philosophy of science. Mechanisms are sets of entities and activities organized to produce a regular series of changes from a beginning state to an ending (McAdam et al. 2008). They usually “invoke some form of ‘causal agent’ that is assumed to have generated the relationship between the entities observed and are analytical constructs that provide hypothetical links between observable eventss” (Hedström and Swedberg 1998). Often mechanisms are generally unobservable or hidden phenomena, sensitive to variations in context, but empirically traceable processes that act as a cause in generating the outcome (Pawson and Tilley 1997). Assessing the logic of association helps us open the black box of the limited X → Y causal inferences so prevalent in the social sciences. Causality is not simply a functional description of a certain variable but requires uncovering how X actually produces Y under specific conditions. Rather it is a theoretical formulation that “adduces properties of the relationships among phenomena with the potential to recur, which helps explain why x causes y” (Hall 2013, p. 21). What is important is the context to this relationship and the role it plays in determining outcomes. Initial conditions play a key role in determining how mechanisms are triggered and how they respond to certain contextual conditions. Identifying the context and the mechanism is important when formulating research hypotheses. It is critical to understand under what conditions that mechanisms are most likely to occur or produce a particular outcome (Pawson and Tilley 1997). Various scholars have adopted “context-mechanism-outcome” (CMO) approach: namely, the observed patterns of (un)intended outcomes can be explained by identifying the plausible causal set of mechanisms within the situational context of the process (Fig. 1) (Pawson and Tilley 1997). Key aspects of a “setting” influence when and how certain mechanisms are triggered and how they play out. Context is also critical because similar initial conditions may lead to dissimilar outcomes (multifinality) and those outcomes can be reached from any number of different developmental paths (equifinality) (Biesbroek et al. 2017).
Fig. 1

Context-mechanism-output (CMO) model. (Source: Pawson and Tilley 1997)

This more robust understanding of causality permits the opening-up of the black or gray boxes of policy-making. In doing so, researchers will find a diversity of causal mechanisms that affect policy outcomes. At first glance, there are different broad mechanism types: structural (e.g., environment, institutions), cognitive (e.g., individual perceptions and ideas), and relational (e.g., network connections between people). Second, mechanisms can span between micro-level (individual) and macro-level (structural) phenomena (Bunge 1997). Given the multilevel nature of policy-making, these mechanisms are particularly important. These are illustrated in Fig. 2. “Situational” mechanisms occur when social structures or environmental phenomenon constrains individuals’ action or shape and beliefs. “Action-formation” mechanisms link individual micro-level activities or behavior to their actions.
Fig. 2

“Bathtub” approach for identifying different levels of mechanisms. (Adapted from Hedström and Swedberg 1998)

Transformational mechanisms are those in which individuals, through their actions and interactions, generate intended and unintended outcomes. Third, researchers need to be aware of the temporal nature of mechanisms which includes the time horizons of both the mechanism and outcome (Beach and Pedersen 2013). For example, some slow-moving causal processes result in a threshold event resulting in a sudden change. In the policy and public management, there are many examples of mechanisms that fit these high-level albeit somewhat abstract mechanisms. It is also critical that more compelling and measurable causal explanations can only be realized if mechanisms are disaggregated from a high level of abstraction, which they label as “processes,” “mechanisms-as-type,” and “mechanisms-as-example” which explains why things happen. Making a measurable causal claim and describing how things happen require attention to “mechanisms-as-cause” and “mechanism-as-indicators (Falleti and Lynch 2008).” Thus, mechanisms are often nested hierarchies that contain “lower level entities, properties, and activities” that “produce higher level phenomena” (p. 13). Machamer et al. (2000) borrow from molecular biology and find that mechanisms “bottom out in descriptions of the activities of macromolecules, smaller molecules, and ions” (p. 14).

Mechanistic-Based Policy Analysis

Process-based analysis is critical because “when the procedural sides of a policy making or decision-making process have been thought through properly, it will greatly increase the likelihood of substantive problems being resolved” (Mayer et al. 2013, p. 181). The policy research and analysis communities should be interested in testing policy mechanisms so as to measure policy-oriented causal inferences and explain outcomes in more practical terms. Policy and public management research is often based on small N between-case and within-case studies. When the mechanisms are known, analysts can collect diagnostic evidence, theorize variables and empirical proxies, and test hypotheses which then provide a narrative explaining how a particular outcome or set of events came about (Kay and Baker 2015).

Testing hypotheses can be achieved through rigorous methods such as process tracing and qualitative comparative analysis (QCA) which are two popular methods for capturing causal mechanisms in action. Rather than testing for probability, analysts consider necessary and sufficient conditions as their criteria (Kay and Baker 2015). Necessity refers to the situation that the outcome cannot be produced without a condition, whereas sufficiency refers to the situation in which a condition itself can produce the outcome without the help of other conditions. Process tracing can involve understanding a simplistic change of events related to a single phenomenon, the convergence of a number of conditions, or complex interactions causal factors (Meyfroidt 2016; Trampusch and Palier 2016). This is often achieved by converting narratives into mechanistic explanations. Beach (2017) argues that analysts can develop minimalist or systematic understandings of mechanisms. A minimalist approach considers only diagnostic evidence. A systematic approach explicitly unpacks the causal process and delves into understanding the empirical fingerprint that the mechanism makes and unpacking it into its constituent parts. In part, this can be a function of the variety of information sources collected (archival documents, interviews, reports, memos) that are accumulated over a given period of time (Charbonneau et al. 2017).

Beach and Pedersen (2013) identify three types of “process tracing”: theory testing, theory building, and explaining outcomes. Theory-testing process tracing is employed when a phenomenon X is causing outcome Y that is known but the mechanism is not specified. Since mechanisms are portable concepts, they can be applied by policy researchers to further elaborate the long-term nature of policy change. Alternatively, in theory-building process tracing, the relationship between X and Y is detected, but the researcher cannot identify the mechanism or when the outcome (Y) is known, but X is unknown. In both cases, the researcher develops a new mechanism. Beach and Pedersen (2013) describe Janis’ (2013) development of “groupthink” mechanism as the cause of the Bay of Pigs fiasco. Theory building would require considerably more time and effort than theory testing. In explaining-outcome process tracing, the outcome (Y) is known, but X is unknown, or the researcher is interested in fully explaining why X happened. In each type of process tracing, the analyst will develop a causal mechanism. The second step involves operationalizing the mechanism based on “observable manifestation” from different types of evidence. From collecting such information, the inferential weight of the evidence and the hypotheses can be assessed using four well-known tests that apply Bayesian probability (straw in the wind, hoop, smoking gun, and double-decisive tests) (See Van Evera 1997). These tests examine necessary and/or sufficient conditions for inferring evidence from the hypotheses that exist. The principles of certainty and uniqueness of the evidence reflect the necessary and sufficient conditions. The straw-in-the-wind test supports or weakens a hypothesis but does not exclude it. The smoking-gun test confirms the hypothesis but does not exclude other hypotheses. Hoop tests reject a hypothesis but do not influence other hypotheses. Finally a double-decisive test confirms a single hypothesis and disconfirms other rival hypotheses. Often researchers will be interested in comparing a number of cases, for example, comparing climate change policy in a number of jurisdictions. Qualitative comparative analysis (QCA) is popular approach which applies set theory and conceives cases as configurations of attributes. QCA examines thes necessary and sufficiency of configurations of conditions combined to generate outcomes and enable causal interpretation (Ragin 2014).


Causal mechanisms have been overlooked because they are usually hidden but are sensitive to variations in context. A toolkit equipped with well-elaborated mechanisms is not only useful for precision and depth to understand the generative processes of existing theoretical models but is also valuable for empirical research and enhancing policy-making decisions (Tranow et al. 2016). Thus, the policy scholar, scientist, and public official can benefit from deeper understanding of causal mechanisms. Policy scholars should take up the challenge and identify more specific mechanisms via process tracing in existing social science theories or develop new mechanisms. This may lead to improving, changing, or refuting the broad and sometimes vague assumptions about existing theories and frameworks. By doing so, academic researchers will be able to undertake richer empirical work.



  1. Beach D, Pedersen R (2013) Process-tracing methods: foundations and guidelines. University of Michigan Press, Ann ArborCrossRefGoogle Scholar
  2. Beach D (2017) Process-Tracing Methods in Social Science. In Oxford Research Encyclopedias of Politics. Oxford University Press. http://politics.oxfordre.com/view/10.1093/acrefore/9780190228637.001.0001/acrefore-9780190228637-e-176CrossRefGoogle Scholar
  3. Biesbroek R, Dupuis J, Wellstead A (2017) Explaining through causal mechanisms: resilience and governance of social-ecological systems. Curr Opin Environ Sustain 28:64–70CrossRefGoogle Scholar
  4. Bunge M (1997) Mechanism and explanation. Philos Soc Sci 27:410–465CrossRefGoogle Scholar
  5. Charbonneau É, Henderson AC, Ladouceur B, Pichet P (2017) Process tracing in public administration: the implications of practitioner insights for methods of inquiry. Int J Public Adm 40(5):434–442CrossRefGoogle Scholar
  6. Falleti TG, Lynch J (2008) From process to mechanism: Varieties of disaggregation. Qual Sociol 31(4):333–339CrossRefGoogle Scholar
  7. Hall PA (2013) Tracing the progress of process tracing. Eur Polit Sci 12(1):20–30CrossRefGoogle Scholar
  8. Hedström P, Swedberg R (eds) (1998) Social mechanisms: an analytical approach to social theory. Cambridge University Press, CambridgeGoogle Scholar
  9. Kay A, Baker P (2015) What can causal process tracing offer to policy studies? A review of the literature. Policy Stud J 43(1):1–21CrossRefGoogle Scholar
  10. Machamer P, Darden L, Craver CF (2000) Thinking about mechanisms. Philos Sci 67(1):1–25CrossRefGoogle Scholar
  11. Mayer IS, van Daalen CE, Bots PWG (2013) Perspectives on policy analysis: a framework for understanding and design. In: Public policy analysis. Springer US, Boston, pp 41–64CrossRefGoogle Scholar
  12. Meyfroidt P, (2016) Approaches and terminology for causal analysis in land systems science. J Land Use Sci 11(5):501–522CrossRefGoogle Scholar
  13. McAdam D, Tarrow S, Tilly C (2008) Methods for measuring mechanisms of contention. Qual Sociol 31:307–331CrossRefGoogle Scholar
  14. Pawson R, Tilley N (1997) Realistic evaluation. Sage, LondonGoogle Scholar
  15. Ragin CC (2014) The comparative method: moving beyond qualitative and quantitative strategies. University of California Press, OaklandGoogle Scholar
  16. Tilly C (2001) Mechanisms in political processes. Annu Rev Polit Sci 4:21–41CrossRefGoogle Scholar
  17. Trampusch C, Palier B (2016) Between X and Y: how process tracing contributes to opening the black box of causality. New Polit Econ 21(5):437–454CrossRefGoogle Scholar
  18. Van Evera S (1997) Guide to methods for students of political science. Cornell University Press, IthacaGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  • Adam M. Wellstead
    • 1
    Email author
  • Paul Cairney
    • 2
  • Kathryn Oliver
    • 3
  1. 1.Department of Social SciencesMichigan Technological UniversityHoughtonUSA
  2. 2.Division of History and PoliticsUniversity of StirlingStirlingUK
  3. 3.London School of Hygiene & Tropical MedicineLondonUK