Scientific ideas are difficult to teach, difficult to learn, and difficult to accept as true because they contradict our intuitive theories of the world, constructed in childhood but retained across the lifespan, influencing our thinking even as adults. In this chapter, I discuss what intuitive theories are, where they come from, and why they blind us to more accurate theories of the world. I explore two case studies – projectile motion and evolutionary adaptation – to illustrate how intuitive theories are historically entrenched, culturally widespread, resistant to counterevidence, maladaptive for behavior, and seemingly inerasable. I conclude by considering the impact of intuitive theories on human belief and behavior more generally.

In Chapter 2 I argue that we reason by building and manipulating mental models. These causal models allow us to predict, control and explain the world around us. They are idealized and schematic, which reduces complexity but can lead to reasoning biases. I also present an account of how we generate these models, by using intuitive theories of how things work and how humans behave. This allows for learning and inference at multiple levels, and it helps explain our proficiency at explaining the world.