ABSTRACT
This chapter examines the biological and social functions played by the face (or by the organ it hosts), tracing them back to their evolutionary history. The face turns out to be functionally overcrowded. Then, drawing on some notions from the philosophy of artifacts, the chapter sketches a theory and a taxonomy of masks. Masks are construed as artifacts whose function is to interact with some of the functions of the face. They are sorted into different categories, depending on which functions of the face they are intended to act upon. The chapter also considers some interesting phenomena that complicate functional attributions. These considerations are then applied to a specific type of mask, namely the medical face mask.
