Abstract

Expertise is a major topic in the thoughts of Socrates, Plato, and Aristotle in the West, as well as in the thoughts of Daoist and Buddhist philosophers in the East. Expertise interests ancient philosophers due to the distinctive phenomenology of expertise, the puzzle surrounding the relationship between declarative knowledge and expertise, the practical process of expertise formation, and the use of expertise acquisition as a model for ethical and epistemic development. Philosophical interest in expertise has resurfaced in the last century, particularly regarding the phenomenology of expert performance, the relation between knowledge and expertise, and expertise-based models of ethical and epistemic virtues. What is missing from current philosophy is an account of expertise change. The ancients are concerned with how expertise changes within an individual’s lifetime. With the advent of Darwin’s evolutionary theory, the question of expertise change adds another dimension: how does expertise change within a human group over successive generations? My dissertation is about both types of expertise change. I define expertise as skills that take at least years of effective training for most people to develop. A proper account of expertise change needs to describe its pattern since the beginning of our species. Foragers in the late Pleistocene were already experts at crafting and hunting. Take hunting as an example. Modern foragers’ children follow older children to play hunting games using toy weapons; adolescents hunt with adults and copy hunting tricks from the mature hunters (for a recent review, see Lew-Levy et al. 2017). For certain types of prey, average hunting proficiency reaches its peak after decades of social learning. Richerson, Boyd, Henrich, and Heyes propose to explain change in expertise through cultural evolutionary theory (Boyd and Richerson 2005; Henrich 2015; Boyd 2018; Birch and Heyes 2021). They define culture as socially inherited information stored in the brain capable of explaining behavior. Expertise is a subcategory of culture that no individual can invent alone, or what I call NICIA culture (Richerson and Boyd 2005; Henrich 2015; Boyd 2018). NICIA culture is produced through the historical accumulation of cultural innovations, which I call historical cultural change. The possibility of historical cultural change is supported by population models analogous to those in population genetics. Godfrey-Smith (2009, chapter 8) describes population models as a broader category that subsumes selectionist models as a subset. In population models, individuals within the population are of a similar type, sharing many common properties. Formal analysis or simulation, when applied to population models, can help derive population-level dynamics from the aggregated effect of one-on-one interactions at the individual level. I follow Lewens (2015) by referring to Richerson, Boyd, and Henrich’s population models as kinetic models. My dissertation aims to criticize the use of kinetic models to explain historical cultural change. I think that the primary utility for explaining historical cultural change is to explain expertise change, but if we look closer at how individuals develop expertise, kinetic explanations of expertise change lose their attraction. In chapter 2, I argue that the primary utility for positing historical cultural change is to explain expertise change. Cultural evolutionary theorists posit historical cultural change to explain the emergence and maintenance of NICIA culture. However, NICIA culture is defined in a negative way, which renders it notoriously difficult to operationalize. A more useful conceptual framework needs a positive description of the kind of culture that requires historical explanation. I argue that the positive description of developmental complexity, i.e., the required time for learning, can partially replace the role of NICIA culture in specifying the scope of cultural evolutionary models. Since expertise is a developmentally complex skill, the main point of explaining historical cultural change is to enhance our understanding of expertise change. If a cultural evolutionary model fails to explain expertise change, then the model loses significant motivation. The phenomena subsumed under the category of expertise are still too heterogeneous. In Chapter 3, I argue that expertise can be roughly classified in a three-dimensional space according to three types of training required to acquire it: the demands of virtuosic training, the demands of improvisational training, and the demands of physical training. Effective virtuosic training depends on deliberate practice (Ericsson et al. 1993). Effective physical training depends on repeating the same training activity at appropriate temporal intervals. Sustenance expertise of late Pleistocene foragers, as well as moral expertise, scientific expertise, chess, and psychotherapy, are expertise domains that are high in improvisational demands, but not necessarily high in virtuosic and physical demands. I argue that expertise in these domains is mostly gained through effective improvisational training, which crucially depends on the variation in training experience. I argue that neither selectionist models nor the more liberal kinetic models are useful in explaining change in improvisational expertise. I discuss problems with selectionist models of expertise change in Chapter 4 and problems with kinetic models in Chapter 5. What causes problems for both types is the vague teacher-student lineages of improvisational expertise. One cannot attribute the development of improvisational expertise solely to the teaching of one master; the result of training must always be attributed to the entire guild, including its environment. In the latter half of Chapter 5, I delimit the proper scope for cultural selectionist models in explaining expertise change. I think they are useful at least when (1) the focal traits are much simpler than expertise but still relevant for expertise acquisition, and (2) the aspect of expertise change being explained is limited to the maintenance and stabilization of expertise acquisition. I situate this aspect within a more fine-grained description of the historical patterns of expertise change. The last chapter, chapter 6, critically examines the popular description of cultural change at the population level as being faster than biological change. Richerson and Boyd use this seemingly obvious statement to explain why sustenance expertise remains a cultural trait instead of being genetically assimilated. I analyze the kind of evolutionary speed comparison between cultural and biological change that is required to support this built-for-speed explanation of the stable cultural status of expertise, and I reject such speed comparisons as inoperationalizable. It may seem that some cultural traits transform faster than some morphological traits, but very little can be inferred from such cross-trait speed comparisons.

Committee Chair

Anya Plutynski

Committee Members

Carl Craver; Kent Staley; Pascal Boyer; Ron Mallon

Degree

Doctor of Philosophy (PhD)

Author's Department

Philosophy

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

7-30-2025

Language

English (en)

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