Standard views on surrogate decision making present alternative ideal models of what ideal surrogates should consider in rendering a decision. They do not, however, explain the physician's responsibility to a patient who lacks decisional capacity or how a physician should regard surrogates and surrogate decisions. The authors argue that it is critical to recognize the moral difference between a patient's decisions and a surrogate's and the professional responsibilities implied by that distinction. In every case involving a patient who lacks decisional capacity, physicians and the treatment team have to make judgments about the appropriateness of both the surrogate and the surrogate's decision. They have to assess the surrogate's decisional capacity and attitude toward the patient as well as the reasons that support the surrogate's decision. This paper provides a model for acceptable surrogate decisions and a standard for blocking inappropriate surrogates. Only decisions based on widely shared reasons are allowable for surrogate refusal of highly beneficial treatment.