Valid consent is morally transformative: with valid consent, sex is not rape, a medical exam is not assault, and entering a person’s home is not trespass. But saying “yes” does not always constitute valid consent (e.g. if coerced). The received view in moral philosophy and bioethics is that valid consent is autonomous consent. Autonomy involves capacities to make rational and authentic decisions—to make informed, rational choices on the basis of one’s own values. But even if someone has the capacity to decide autonomously, they might not exercise that capacity on a particular occasion. For instance, they might decide in an irrational, whimsical, or inauthentic way. In this talk I explore what kind of autonomy is required for valid consent. Firstly, I argue that the folk concept of valid consent is relevant to ethical theorizing about consent, and I present evidence from a series of studies showing that ordinary people view consent as valid so long as the agent possesses autonomous decision-making capacities, even she does not make this particular decision rationally or authentically. Secondly, I explore the ethical implications of these findings. These findings weaken scepticism about the consent of agents who are subject to nudging or other biases, and weaken related arguments for paternalist interference in medical decisions. Furthermore, I suggest we rethink the exact role of patient autonomy in medical ethics. Whilst the exercise of autonomous decision-making capacities ought to be treated as a value to be promoted and supported, the decisions of patients who possess them—even if these particular decisions are irrational, whimsical, inauthentic, or otherwise not fully autonomous—must be respected and treated as morally transformative.