The Natural Kinds Behind the Average: The Ontological Turn of Individual and Type in the Victorian Statistical Movement

The concept of the average is not only a mathematical calculation but also a question of metaphysics and morality. Throughout the Victorian period, statisticians such as Adolphe Quetelet and Francis Galton grappled with the "average" in many ways: Is it an a priori entity or a mere division of the total? Is it an ideal or a mediocrity? Is it real or artificial? Is it normative or purely objective? Intertwined with these debates are constellations of social refinement, value judgment, ideological commitment, and, most importantly, ontological assumptions. In 1835, Quetelet introduced the concept of "the average man" (l' homme moyen) in his Sur L' Homme, while in 1878, Galton conceived the photographic technique of "composite portraits" to visualize the average face of the criminal type. Although both ideas center on the "average," they reflect fundamentally different ontologies concerning the relationship between individuals and types—a contention originally rooted in the classical opposition between Platonic and Aristotelian views on natural kinds. The Platonic perspective posits that types exist as idealized, independent entities prior to individuals. In practice, it often carries subjective and value-laden interventions and idealizations. In contrast, the Aristotelian view sees types as inherent within individuals, inseparable from them. Underlying the Platonic view on natural kinds by forming the type transcending the individual, Quetelet's "average man" is an abstract, a priori entity that evolved from "the centre of gravity in bodies" to a spiritual archetype that "represents the type of that nation," and even to "the type of all which is beautiful – of all which is good." More than merely a calculated result, the "average man" praised by Quetelet represented his eclecticism while intrinsically embedding the egalitarian mentality of individualism and democracies in an era of political upheaval. On the contrary, Galton's composite portrait as a synthesis scheme effectively reconciled the conflict between finding an idealized prototype and conforming to "mechanical objectivity." Therefore, unlike Quetelet's Platonic approach, Galton's composite portraits aligned with an Aristotelian "characteristic": one cannot deduce the type independently of individuals. Through objectively composing multiple individual portraits into an integrated one, Galton's focus lay not on either moral or metaphysical implications behind the "average." Rather, he dismissed it as mediocre and "but a solitary fact," while emphasizing the importance of "variations." Although producing average faces, his composite portraits solely focus on those outliers and deviations, such as criminals and degenerates, whom he termed "undesirables" within society, thus resonating with the eugenic perspective inherent in Galton's statistical purposes. This paper argues that the contention over the relationship between individuals and types shaped the Victorian Statistical Movement through differing interpretations of the average, and continues to ethically influence scientific practices in classification, identification, and pattern recognition across disciplines such as medicine, astronomy, and computer science.