I treat the mind as a biological question: language and thought are adaptations that extend abilities we share with other animals. For well over a century, this has been the standard scientific approach to other mental capacities such as vision and motor control. But language and thought, even now, are usually studied as abstract formal systems that just happen to be implemented in our brains. […] Understanding language and thought requires combining findings from biology, computer science, linguistics, and psychology. A theory that seems perfectly adequate from one perspective may contradict what is known in another field. Problems that seem intractable in one discipline might be quite approachable from a different direction. Taking all the constraints seriously is the only way to get it right.