Routinely, in Arriving at decisions on what treatments to recommend in intensive care wards, the moral presumption is that there is an intrinsic difference between the positive duty to save lives and the negative duty not to take lives. The discontinuation of treatment – say stopping chemotherapy or removing a ventilator – is thought of as a “negative” action, an allowing to die, not “positively”, say as an act of suicide by the patient, or a killing by the hospital staff. But the distinction between “positive” and “negative” here, despite its grave ethical import, is elusive and difficult to grasp firmly. St. Anselm of Canterbury was fond of citing the trickiness of the distinction between “to do” (facere) and “not to do” (non-facere). In answer to the question “What's he doing?” we say “He's just sitting there.” (positive), really meaning something negative: “He's not doing anything at all.” Sometimes the “negative” action is described in “positive” terms, or vice versa, and that makes one wonder if the distinction might be somehow trivial, a bit of jesuitry too insubstantial to bear much serious ethical weight.