In this paper, we assess the possibility of a critical knowledge of technology. In the case of facial recognition systems, ‘FRS’, we argue that behaviorism underlies this technology, and analyze the debate about behaviorism to show the lack of consensus about its theoretical foundations. In particular we analyze the structure of knowledge generated by FRS as affected by a technological behaviorism. Our last point is a suggestion to use the concept of ‘critical knowledge’, which we borrow from Ladrière, to question and challenge the technological finalities and the foundational scientific theory underlying FRS.