In this paper I reconsider debates in the Australian colonies in the 1830s and 1840s about Aboriginal people and rights in land. I contend that Aboriginal rights of property in land were seldom the matter at stake in these debates. Further, I argue that a notion of duties rather than rights was invoked by Christian humanitarians as they pleaded that Aboriginal people should be provided with protection as well as compensation for the loss of their lands. I suggest that the position that they adopted was determined not so much by the moral, political or legal principles they sought to uphold but by their acknowledgement of material forces at work in the colonies. I also point out that the debate that occurred about rights in land was an intra-British one that concerned the rights of settlers vis-à-vis the Crown. Finally, I suggest that the principal ways in which pastoral leaseholders tried to legitimise their claims to land were rather different to that suggested by historians in recent decades.