In this paper, we discuss how the increasing prevalence of Speculative Design in educational, research and commercial contexts may reflect and nurture a challenge to the dominance of ‘scientism’. The successes associated with 20th-century modernism are now, in the 21st-century, key factors in the intractability and complexity of 21st-century challenges. Speculative and Design-led approaches offer practical means to break down such intractability but do so over relatively short timeframes. We argue that, if we adopt a longer-term perspective, then disrupting the dominance of scientism so that the benefits of Speculative Design are ‘built in’ rather than ‘added on’ is realistic and desirable. In exploring this proposition, we come to reason that the ultimate measure of Speculative Design’s success is to disappear completely.