Michael Commons

Introduction

Michael Lamport Commons (born 1939) is an American theoretical behavioral scientist best known for the Model of Hierarchical Complexity, an attempt to define developmental stages by the structure of tasks rather than by the mental structures of the people performing them.

That distinction is the whole point of his work. Jean Piaget described stages as properties of the child's mind; Commons argues that stages can be defined mathematically as properties of actions, independent of who or what performs them — a human adult, a child, an animal, or a machine. If that claim holds, developmental stage becomes something you can measure with the same instrument across species and cultures, which is a far stronger claim than any Piagetian made.

Commons has never held a conventional psychology professorship. He works as an assistant clinical professor in the Department of Psychiatry at Beth Israel Deaconess Medical Center, a teaching hospital of Harvard Medical School, and directs the Dare Institute in Cambridge, Massachusetts, an independent nonprofit research group. Most of his institutional influence has come from founding things: he co-founded the Society for Quantitative Analysis of Behavior, the Society for Research in Adult Development and its European counterpart, the Society for Terrorism Research, and the developmental behavior analysis special interest group within the Association for Behavior Analysis International.

His model has a devoted following in adult development and a persistent skeptical audience among Piagetians and psychometricians, and the disagreement between them has never been resolved.

Early Life and Education

Commons was born in 1939 in Los Angeles and grew up in Hollywood. He studied at the University of California, Los Angeles, where he took two bachelor's degrees — one in mathematics and one in psychology. This double training is the most important fact about his intellectual formation. Almost everything distinctive about the Model of Hierarchical Complexity comes from treating a psychological question as an ordering problem in mathematics rather than as a question about mental content.

He then went to Columbia University for graduate work in psychology, taking an M.A. and an M.Phil. before receiving his Ph.D. in 1973. Columbia at that period had a strong experimental and quantitative tradition, and Commons emerged from it with a commitment to the analysis of behavior rather than to introspective or interpretive accounts of thought — a commitment he retained even as he moved into developmental questions that most behavior analysts avoided.

Two commonly repeated errors about his education are worth correcting. He did not study at the University of California, Berkeley; his undergraduate degrees are from UCLA. And his two bachelor's degrees were separate degrees, not a single combined mathematics-and-psychology degree.

Academic and Professional Career

Commons's career has been built outside the usual departmental structure. Rather than a psychology department chair, he has held a clinical appointment in psychiatry at Beth Israel Deaconess Medical Center — a Harvard-affiliated teaching hospital — and has run his research through the Dare Institute, a group under the umbrella of the nonprofit Dare Association. The Dare Institute, which he has led with Patrice M. Miller, studies the development of decision making across contexts including academia, economics, politics, medicine, and the law, testing children, adolescents, and adults on structured problems.

His model was developed collaboratively. The formal apparatus was worked out with Francis Asbury Richards and, later, with Edward Trudeau and Alexander Pekker. The founding empirical paper — "Systematic and metasystematic reasoning: A case for a level of reasoning beyond Piaget's formal operations," with Richards and Deanna Kuhn — appeared in Child Development in 1982 and is the point at which the program became visible to mainstream developmental psychology.

Much of his subsequent influence flowed through editing rather than authorship. He was senior editor of the eleven-volume Quantitative Analyses of Behavior series, senior editor of four volumes on adult development, associate editor for a special issue of the Journal of the Experimental Analysis of Behavior on the nature of reinforcement, consulting editor of a moral development series, and past co-editor of Behavioral Development Bulletin and the Journal of Behavior Analysis Online.

He has also pursued applications outside academic publishing. With Mitzi Sturgeon White he was issued a patent on intelligent control using hierarchical stacked neural networks — an attempt to implement the stage hierarchy as a machine architecture. He has been associated with Core Complexity Assessments, a company that applies stage-based measurement to hiring and workforce planning.

Major Contributions to Psychology

The Model of Hierarchical Complexity

The Model of Hierarchical Complexity assigns an order of hierarchical complexity to a task, using three conditions: a higher-order action must be defined in terms of two or more lower-order actions, it must organize those lower-order actions, and that organization must be non-arbitrary. If all three hold, the action belongs to the next order up.

Crucially, nothing in this definition refers to a person. The complexity of the task is fixed by the structure of the task itself. A participant's stage is then inferred from the highest-order task they complete correctly. The canonical presentation lists sixteen orders — running from computory and sensory-motor actions through nominal, preoperational, concrete, abstract, formal, systematic, and metasystematic reasoning up to paradigmatic and cross-paradigmatic thought — with a further meta-cross-paradigmatic order added in later versions.

The practical payoff Commons claims is scale generality: because the orders are content-free, the same framework can in principle rank tasks in moral reasoning, workplace decision making, mathematics, and animal learning on one metric.

Postformal Stages Beyond Piaget

Piaget's sequence ends at formal operations, typically reached in adolescence. Commons and Richards argued that this leaves adult intellectual development undescribed, and proposed systematic and metasystematic stages beyond it: reasoning about whole systems of relations, and then reasoning about relations between systems. The 1982 Child Development paper with Richards and Kuhn presented multisystem tasks intended to separate these levels experimentally.

This is the part of his work that made postformal thought a research area with its own journals and societies, and also the part that has attracted the most sustained criticism.

Bridging Behavior Analysis and Development

Commons is unusual in belonging to both the behavior-analytic and developmental camps, which historically ignored each other. He worked to show that hierarchically complex behavior can be described in behavior-analytic terms — for example in work with Joseph A. Rodriguez on hierarchically complex equivalence classes in the Psychological Record — and co-founded the developmental behavior analysis special interest group within the Association for Behavior Analysis International to institutionalize the connection. His comparative work with Lawrence Kohlberg's moral stages, and with Theresa Grotzer on the relation between Piagetian and Kohlbergian stage, belongs to the same integrative project.

Applied Measurement

Commons and colleagues, including Eric A. Goodheart and Theo L. Dawson, applied Rasch measurement models to stage data, arguing that scores from hierarchical complexity tasks form an interval scale rather than an arbitrary ordering. This psychometric turn is what allowed the model to be used in applied settings — assessment of institutional atmosphere, workplace stage development, legal and psychiatric questions about competence, and eventually commercial personnel assessment.

Major Publications

  • Beyond Formal Operations, Vol. 1: Late Adolescent and Adult Cognitive Development (1984), edited with Francis A. Richards and Cheryl Armon. Praeger.
  • "Systematic and Metasystematic Reasoning: A Case for a Level of Reasoning Beyond Piaget's Formal Operations" (1982), with Francis A. Richards and Deanna Kuhn. Child Development, 53, 1058–1069.
  • Adult Development, Vol. 1: Comparisons and Applications of Adolescent and Adult Developmental Models (1989), edited with Jan D. Sinnott, Francis A. Richards, and Cheryl Armon. Praeger.
  • Adult Development, Vol. 2: Models and Methods in the Study of Adolescent and Adult Thought (1990), edited with Cheryl Armon, Lawrence Kohlberg, Francis A. Richards, Theresa A. Grotzer, and Jan D. Sinnott. Praeger.
  • "The Development of Hierarchically Complex Equivalence Classes" (1993), with Joseph A. Rodriguez. Psychological Record, 43, 667–697.
  • "Formal, Systematic, and Metasystematic Operations with a Balance-Beam Task Series: A Reply to Kallio's Claim of No Distinct Systematic Stage" (1995), with Eric A. Goodheart, Linda M. Bresette and colleagues. Journal of Adult Development, 2, 193–199.
  • Quantitative Analyses of Behavior, Volumes 1–11, as senior editor.

Impact and Legacy

The Model of Hierarchical Complexity gave adult development a measurement language it had lacked. Before Commons, claims about adult cognitive growth were largely descriptive; after him, there were tasks, scoring rules, and scale statistics that could be argued about. The societies and journals he founded — particularly the Society for Research in Adult Development and Behavioral Development Bulletin — remain the institutional home of that literature, and his framework is used in organizational development, education, and stage-based assessment of moral and legal reasoning.

The criticisms are serious and largely unresolved.

The most direct empirical challenge came from Eeva Kallio, who in a 1995 Journal of Adult Development study of thirty-five Finnish university students failed to find a distinct systematic stage, reporting instead that full formal operations were not a necessary condition for systematic thinking. Commons and eleven co-authors replied in the same volume, arguing that discrepant multidomain results reflected differences in task, domain, and scoring rather than the non-existence of stages, and reporting that within a single domain — balance beams and their extensions — participants scoring at a higher stage could also perform the lower-stage tasks. The exchange is a fair summary of the dispute's structure: Commons's defense is that his critics measured badly, and his critics' response is that a stage which only appears under his own scoring procedures is not much of a stage.

Kallio pressed the theoretical version of the objection in Theory & Psychology in 2011, arguing that the concepts of relativistic and dialectical thinking underpinning postformal research are ambiguous and weakly defined, and proposing that "integrative thinking" within the formal stage accounts for the phenomena without a new stage. Helena Marchand and Deirdre Kramer made related arguments, and Kohlberg himself expressed reservations about postformal stages. Reviewing the field, critics including Orlando Lourenço and Armando Machado noted that no consensus exists on what distinguishes postformal operations from formal ones, and cited evidence that postformal reasoning — if it is a stage at all — is not logically superior to formal-operational reasoning but rather a parallel, more contextual mode of thought.

A methodological objection cuts closer to the core. Because the order of hierarchical complexity of a task is assigned in advance by the model's own axioms, and the empirical scaling then confirms that people succeed on lower-order tasks before higher-order ones, critics argue the good scale fit is partly guaranteed by the design rather than discovered in the data. Commons's answer is that this is exactly the model's virtue: defining complexity independently of performance is what makes the ordering a theoretical prediction rather than a factor-analytic artifact, and the prediction could in principle fail — people could master higher-order tasks first, and they do not.

A third concern is applied rather than theoretical. Using stage scores to sort job candidates, as Core Complexity Assessments proposes, requires predictive validity for job performance that the developmental literature has not established, and raises the same fairness questions that attach to any cognitive test used in hiring.

The net position is that Commons produced the most formally explicit stage model in developmental psychology, and that its central empirical claim — a genuine, separable stage of adult reasoning beyond formal operations — remains contested more than forty years after it was proposed.

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References

  • Commons, M. L., & Richards, F. A. (1984). A general model of stage theory. In Beyond Formal Operations. Praeger.

Last updated: 2026-10-20

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