 Neuroethics is driven by neurotechnologies: it is concerned with the ethical questions that attend the development and effects of novel neurotechnologies, as well as other ethical and philosophical issues that arise from our growing understanding of how brains give rise to the people that we are and the social structures that we inhabit and create. These questions are intimately bound up with scientific questions about what kinds of knowledge can be acquired with particular techniques: what are the scope and limits of what a technique can tell us? With many new techniques, answers to these questions are obscure not only to the lay public, but often to the scientists themselves. The uncertainty about the reach of these technologies adds to the challenge of grappling with the ethical issues raised.