What is "critical" about critical design?

Critical design is a research through design methodology that foregrounds the ethics of design practice, reveals potentially hidden agendas and values, and explores alternative design values. While it seems to be a timely fit for today's socially, aesthetically, and ethically oriented approaches to HCI, its adoption seems surprisingly limited. We argue that its central concepts and methods are unclear and difficult to adopt. Rather than merely attempting to decode the intentions of its originators, Dunne and Raby, we instead turn to traditions of critical thought in the past 150 years to explore a range of critical ideas and their practical uses. We then suggest ways that these ideas and uses can be leveraged as practical resources for HCI researchers interested in critical design. We also offer readings of two designs, which are not billed as critical designs, but which we argue are critical using a broader formulation of the concept than the one found in the current literature.