The EUTF aims to address the ‘root causes of migration’ by providing development assistance to countries of origin and transit. While it is allegedly based on scientific evidence, scholarly consensus suggests that development assistance is ill-suited to address irregular migration – which is something that some of the actors who designed the EUTF were aware of. We advance a new framework for understanding the emergence and success of pseudo-causal narratives (i.e., narratives relying on unproven and/or disproven causal claims) in EU policymaking. Using frame analysis, we argue that the pseudo-causal ‘root causes’ narrative was adopted against better evidence because it was plausible, compelling and had been used in EU external migration policies before. Faced with the salience of migration and the urgency to act in late 2015, and due to the absence of any clear ideas of what other measures could work, EU actors adopted this narrative to demonstrate that they were actively responding to the ‘crisis’. The narrative met little contestation, since it met the concerns of both those who were keen to stop migration and those who wanted to preserve the core of previous EU development policy.