In this paper, we propose that an increasingly regarded theoretical framework in neuroscience--the predictive processing framework--can help to advance an understanding of the foundations of critical thinking as well as provide a mechanistic hypothesis for how education may increase a learner's subsequent use of critical thinking outside of an educational context. We begin by identifying a lacuna in the understanding of critical thinking: a causal account of the internal triggers to think critically. We then introduce the predictive processing framework to address this lacuna, and unpack the implications of this framework for understanding the deployment of critical thinking skills in situ, in the real world.