Should ’géobiologie’ be used or challenged?

Drawing on an ethnographic study conducted in Brittany and the Pays-de-la-Loire region, this article analyses the conditions under which a form of expertise, ’géobiologie’ applied to livestock farming, is both recognized and undermined within the context of controversies surrounding electrical infrastructure. On farms facing health and production problems, ’géobiologie’ functions as a pragmatic inquiry aimed at providing ’insights’ into uncertain phenomena. By combining intuitive practices, instrumental measurements and shared narratives, it carries out a process of (re)defining these disturbances, thereby enabling action to be stabilized temporarily and local intelligibility to be restored. However, when the scale of these interventions changes and they become part of public controversies linked to the siting of energy infrastructure, ’géobiologie’ is subjected to different modes of scrutiny. The article thus demonstrates how locally recognized expertise can be marginalized when exposed to broader normative frameworks, revealing that expert legitimacy depends on the arenas in which it is engaged and the types of evidence prevailing there.