Bruno Latour is a French philosopher, anthropologist and sociologist. His complex interdisciplinary work bears on the epistemology of the natural and the social sciences, and on the social construction of the sciences and technology. We shall first consider Latour's epistemological theses, and his related theoretical contributions; then, his ethnographic research on how scientific facts are socially constructed in laboratories and applied to objects that are at once human and nonhuman. Subsequently, attention will be paid to his research on the history of sciences and technology, such as his investigation on how Pasteur built a reputation as a leading scientific authority in France and elsewhere. Finally, Latour's new democratic project, which conforms to his vision of politics and science, will be summarized. A brief and selective presentation of the secondary literature on Latour will conclude this chapter.

Latour's Basic Concepts

Latour has authored a complex terminology, whose key concepts refer to the interconnections of the component elements of any discourse, and to the rejection of all reductionist tendencies (cf. Schmidgen 2015: 135). This terminology must be now selectively recalled for the sake of clarity. Latour's epistemological interests concern both the social and natural sciences and are accordingly interdisciplinary. These interests have found expression in his Actor Network Theory (ANT). The notion of actor has been reconceptualized as “any entity that modifies another entity in a trial” (Latour 2004: 237), actor being defined here as “an association of humans and nonhumans in a state of uncertainty” (Latour 2004: 75). As interpreters have made it clear, in keeping with Latour the notion of actor should be defined formally, not substantively, as “self-animated ontologies” (Jansen 2017: 203), wherein ontological questions must be understood as “questions about what, and in what way, something has to be, before it can properly called ‘objective’, ‘visible reality‘(De Vries 2016: 10).

Humans and nonhumans form a multiplicity of unbroken associations having “uncertain boundaries.” There is no reason— Latour contends— to deny them the designation of social actors (Latour 2004: 76), as long as it is clear that distinguishing between humans and nonhumans is but “a gross approximation.” For these two categories exist only as traces, routes, displacements (Latour 2007: 35).