This paper aims at contributing to the epistemological reflection on the relationship between French ESP researchers and their research object: English for Specific Purposes. The author first defines the position of French ESP researchers in relation to their research object, using the insights afforded by social science, and more particularly reflexive practice as highlighted by Pierre Bourdieu. Such an approach is particularly adapted to the analysis of specialized domains that do not correspond to any academic discipline and are thus more difficult to comprehend for French ESP researchers. The paper examines this question at greater length by showing how researchers can rely on their experience as language specialists to compensate for the unavailability of any disciplinary framework in the targeted specialized domain to guide their steps.