The term ‘human nature’ can refer to different things in the world and fulfil different epistemic roles. Human nature can refer to a classificatory nature (classificatory criteria that determine the boundaries of, and membership in, a biological or social group called ‘human’), a descriptive nature (a bundle of properties describing the respective group’s life form), or an explanatory nature (a set of factors explaining that life form). This chapter will first introduce these three kinds of ‘human nature’, together with seven (...) reasons why we disagree about human nature. In the main, this chapter focuses on the explanatory concept of human nature, which is related to one of the seven reasons for disagreement, namely, the scientific authority inherent in the term ‘nature’. I will examine why, in a number of historical contexts, it was attractive to refer to ‘nature’ as an explanatory category, and why this usage has led to the continual contestation of the term within the sciences. The claim is that even if the contents of talk about ‘nature’ varied historically, the term’s pragmatic function of demarcation stayed the same. The term ‘nature’ conveys scientific authority over a territory; ‘human nature’ is a concept used to divide causes, as well as experts, and thereby conquer others who threaten to invade one’s epistemic territory. Analysing this demarcation, which has social as well as epistemic aspects, will help us to understand why the explanatory role has been important and why it is unlikely that people will ever agree on either the meaning or the importance of ‘human nature’ as an explanatory category. (shrink)