It’s no secret that I think there is some there there when it comes to developmental psychology. However, I must admit theories of psychological development have some weaknesses. One issue we run into right away is that they sound elitist, and for many that’s enough to reject them in the same way some people reject evolutionary psychology and human biodiversity as racist. Sure, developmental psychology can be abused to support status grabs and enforce social hierarchies, and I have no doubt some people intentionally try to do this, but this is not itself evidence against the ideas, just cautions against how we use the insights we draw from them.

The other major problem is that developmental psychology isn’t a category of strictly scientific theories. One of Kegan’s key insights was that developmental psychology is based on phenomenological methods and capta rather than scientific methods and data. This presents a problem when you try to evaluate developmental psychology through the lens of science as Sarah Constantine recently noted:

Overall, the experimental evidence that distinct, cumulative stages of human development exist is rather weak. The strongest evidence is for Kohlberg’s stages, and these (like all the other stages considered) are limited by the fact that they are measures of how people talk about moral decision-making, rather than what they decide in practice.

Higher stages correlate with positive results in many cases: people at higher Kohlberg stages are less likely to be criminals or delinquents, positive psychological strengths like self-esteem correlate with the Eriksonian ego strengths, and leadership development measures correlate with Kegan stage. This is evidence that developmental stages do often correspond to real psychological strengths or skills with external validity. We just don’t generally have strong reason to believe that they progress in a developmental fashion.

And given that phenomenological methods are not well developed because there are few folks trying to rigorously apply them relative to the way folks apply scientific methods, it’s reasonable to reject the notion that we should trust results based on phenomenology. Developmental psychology might be pointing at real phenomena, but phenomenological theories of developmental psychology are going to fail to meet standards of scientific proof. For developmental psychology to become a more widely accepted theory, it needs to be reformulated in scientific terms.

Michael Commons has done exactly this with the model of hierarchical complexity, or MHC.

MHC takes developmental psychology and reverses its normal etiology. Rather than positing stages that give rise to behaviors, MHC considers individual behaviors and then gives a system of classifying their complexity. The classification is hierarchical, so behaviors in higher complexity classes are necessarily constructed from combinations of less complex behaviors, and the classifications match the shape of developmental psychology as discovered by Piaget and Erikson, but the hierarchy is derived independently via a mathematical abstraction.

MHC’s formulation allows it to accomplish several things at once:

• Developmental stages can correspond to statistical averages of the complexity of behavior instead of making demands that we interpret thought processes.
• MHC can be tested via scientific methods because it’s based on classifying observed behavior rather than classifying self-reported thoughts.
• Multiple theories can attempt to explain the evidence without MHC itself making strong theoretical claims, and MHC remains useful when not used to support theories of developmental psychology.
• It extends to animals we can’t collect phenomenological data on because they can’t communicate it to us, even if it seems likely they have complex thoughts.

This is much of what I was attempting to do with classes T through H in phenomenological complexity classes, but MHC has the advantages of being more thought out over more years and having more conventional theoretical foundations. Not that MHC necessarily displaces phenomenological complexity classes, Kegan’s constructive developmental framework, or others, but it does reduce how much these theories must claim by phenomenological methods alone. MHC seems a powerful bridge between scientific and phenomenological methods of understanding human thoughts and behaviors.

Thanks to Map and Territory reader Dennis Pachernegg for pointing me in the direction of Commons’s work