In this chapter we analyze the rhetorical work of speculative design methods to advance third wave agendas in HCI. We contrast the history of speculative design that is often cited in HCI papers from the mid 2000s onward that frames speculative design as a critical methodological intervention in HCI linked to radical art practice and critical theory, with the history of how speculative design was introduced to HCI publications through corporate design research initiatives from the RED group at Xerox PARC. Our argument is that third wave, critically oriented, speculative design "works' in HCI because it is highly compatible with other forms of conventional corporate speculation (e.g. concept videos and scenario planning). This reading of speculative design re-centers the "criticality" from the method itself to its ability to advance agendas that challenge dominant practices in technology design. We will look at how practitioners trade on the rhetorical ambiguity of future oriented design practices to introduce these ideas in contexts where they may not otherwise have much purchase. Our chapter concludes with a call for critically oriented practitioners in this space to share their experiences navigating speculative design ambiguity and to document the disciplinary history of the method's development.