For those who are interested, a translation of Tarde’s Social Laws: An Outline of Sociology can be found online here. Tarde is one of those underground figures in the thought of Deleuze and Guattari (if memory serves, Deleuze refers to his work as early as Difference and Repetition). Speaking of his importance, Deleuze and Guattari write,

In homage to Gabriel Tarde (1843 – 1904): his long-forgotten work has assumed new relevance with the influence of American sociology, in particular microsociology. It had been quashed by Durkheim and his school (in polemics similar to and as harsh as Cuvier’s against Geoffroy Sain-Hilaire). Durkheim’s preferred objects of study were the great collective representations, which are generally binary, resonant, and overcoded. Tarde countered that collective representations presuppose exactly what needs explaining, namely “the similarity of millions of people.” That is why Tarde was interested in the world of detail, or of the infinitesimal: the little imitations, oppositions, and inventions constituting an entire realm of subrepresentative matter. Tarde’s best work was his analysis of a minuscule bureaucratic innovation, or a linguistic innovation, etc. The Durkheimians answered that what Tarde did was psychology or interpsychology, not sociology. But that is true only in appearance, as a first approximation: microimitation does seem to occur between two individuals. But at the same time, and at a deeper level, it has to do not with an individual but with a flow or a wave. Imitation is the propogation of a flow; opposition is binarization, the making binary of flows; invention is a conjugation or connection of different flows. What, according to Tarde, is a flow? It is belief or desire (the two aspects of every [social] assemblage); a flow is always of belief and desire. Beliefs and desires are the basis of every society, because they are flows and as such are ‘quantifiable’; they are veritable Social Quantities, whereas sensations are qualitative and representations are simple resultants. (A Thousand Plateaus, “Micropolitics and Segmentarity”, 218-219)

It bears repeating that, for Deleuze, the problem of individuation is not the question of how an individual is identified or distinguished from another individual, but rather is the question of how an individual comes-to-be or is produced. As Deleuze will tirelessly repeat, “individuation is not the individual.” Individuation, rather, is an ontological process. In Difference and Repetition, this process is shown to have two dimensions or halves: differentiation and differenciation. Differentiation refers to the differential relations and singularities belonging to a multiplicity and defining a “problematic field”, where a problematic field can be taken as the forces, matters, and tensions a being must navigate in coming to be. Differenciation, by contrast, refers to the manner in which this field is resolved so as to precipitate species, qualities, and parts. For instance, the color of your skin (a quality and part) will be a function of how it is actualized or how it intergrates, sunlight, genetics, diet, and so on. These integrated elements are the problematic field resolved in the course of individuation.

Deleuze and Guattari’s interest in Tarde has to do with how speciation takes place at the level of the social, i.e., those processes involved in subjectivization:

…[S]ocial classes themselves imply ‘masses’ that do not have the same kind of movement, distribution, or objectives and do not wage the same kind of struggle. Attempts to distinguish mass from class effectively tend toward this limit: the notion of mass is a molecular notion operating according to a type of segmentation irreducible to the molar segmentarity of class. Yet classes are indeed fashioned from masses; they crystallize them. And masses are constantly flowing or leaking from classes. (A Thousand Plateaus, 213)

In this particular instance, class would belong to the domain of differenciation, whereas the tensions and forces populating the field of masses would belong to the realm of differentiation. We must not assume a sort of universal human nature where we are born with inherent ways of being affects, of perceiving, of living the world, and so on. For instance, we must not begin with the premise that “humans”, at all times and places, are born with inherent mystical or transcendent experiences, or with the capacity to love as we think it today. Rather, we must examine the way in which bodies are individuated so as to produce these kinds of affects. Niklas Luhmann, for instance, shows how the contemporary experience of love emerged from a particular set of social and historical processes in Love as Passion. Marx shows how new types, sensibilities, subjectivities emerge historically in the bourgeois and proletariat (thereby undercutting a good deal of bourgeois ideology that posits universal human passions such as greed by showing the historical specificity of this sort of subjectivity). A similar ethno-socio-historical analysis could be written for various religious experiences. These are all instances of subjectivization that refer to particular individuations within a social field. The themes here are very close to those Deleuze had explored decades before in his study of Hume, Empiricism and Subjectivity, where he sought to show how Hume is attempting to account for the formation of the subject or how a subject emerges.

I have not yet read the Tarde, but it looks well worth the time.