This article describes the nature, origins and consequences of the epistemological crisis at the heart of contemporary counterterrorism. The epistemological crisis of counterterrorism is an identifiable epistemic posture towards knowledge about, as well as a way of acting towards, the terrorist threat. It manifests itself discursively in the manner in which officials, scholars, pundits and others speak about the threat of terrorism, and the way counterterrorism and security practitioners then act in pursuit of security against that threat. The article argues that many of the bizarre counterterrorist practices regularly observed in many Western countries, as well as costly and counterproductive counterterrorist practices such as preemptive war, targeted killings, mass surveillance, torture, control orders and de-radicalisation programmes, among others, are neither anomalous nor irrational in the context of the new paradigm. Rather, they flow logically and directly from the particular paranoid logic, which is constitutive of the epistemological crisis. The article concludes with a discussion about how and why critical scholars can and should attempt to resist and deconstruct it.