Typically, people know less about how things work than they think they do. We must rely on our communities of knowledge to think productively. One way is through collaboration: The magic of shared intentionality lets us work together with unparalleled effectiveness. But that’s not the only way we rely on our communities. We also outsource. We depend on knowledge that sits elsewhere—In the heads of people we may not be able to identify and in other places—without being aware that we’re doing so. To support this claim, I report evidence that our sense of understanding derives from beliefs about knowledge that we can access; that we consider explanations satisfactory if they appeal to knowledge entrenched in a community even if they carry no information; and that we outsource our moral judgments to the law under certain circumstances. This tribal aspect of cognition dictates how we should represent individual non-expert knowledge: It consists of superficial representations of common ground plus pointers to more detailed representations. These pointers are grounded on relations of trust.