According to the High Court in England and Wales, the primary purpose of legal interventions into the lives of vulnerable adults with mental capacity should be to allow the individuals concerned to regain their autonomy of decision making. However, recent cases of clinical decision making involving capacitous vulnerable adults have shown that, when it comes to medical law, medical ethics and clinical practice, vulnerability is typically conceived as opposed to autonomy. The first aim of this paper is to detail the problems that arise when the courts and health care practitioners respond to the vulnerability of capacitous adults on the basis of such an opposition. It will be shown that not only does the common law approach to vulnerability fail to adequately capture the autonomy of capacitous vulnerable adults, the conception of vulnerability and autonomy in oppositional terms leads to objectionably paternalistic health care responses that undermine the autonomy of vulnerable patients as well as clinical and legal interventions that violate their autonomy. In response, the second aim of this paper is to show that the concepts of autonomy and vulnerability are necessarily entwined and, on that basis, the focus should be on promoting the autonomy of capacitous vulnerable adults where possible. In order to make this case, the paper explains the limitations of standard approaches to the autonomy of vulnerable adults and, in their place, offers a conception of legitimate, self-authorised autonomy that is fundamentally dependent on intersubjective practices of recognition.