Recently, some philosophers of science have argued that epistemology should be extended in order to encompass scientific instruments as material forms of knowledge. One line of argument for this position has consisted in drawing a strong analogy between the traditional concept of knowledge as justified true belief and to argue that what makes the alliance of these three components into proper knowledge can and is satisfied by scientific instruments. Consequently, scientific instruments are not just conductive to scientific knowledge, they are --literally-- scientific knowledge. A materialistic epistemology would then be one that takes seriously the fact that scientific instruments are material objects, the very materiality of which gives them special epistemic properties that traditional epistemology fails to capture.
In contrast, I argue that a materialistic epistemology is better served by adopting a naturalistic approach to knowledge production. More specifically, once we adopt the framework of distributed cognition, the materiality of scientific instruments is amenable to an epistemology of its own and leads to interesting novel insights about how scientific knowledge is produced, used, and justified, while avoiding the difficulties of the analogy-based line of argumentation.