The potential shortage of ventilators during the COVID-19 crisis has resulted in guidelines being published denying any moral difference between withholding and withdrawing medical treatment. This reflects some ethicists' support for ‘the equivalence thesis’, the idea that wherever it is permissible to withhold treatment, it is permissible to withdraw it, and vice versa. Some ethicists claim that doctors' opposition to the equivalence thesis discourages treatment withdrawal, leading to unnecessary loss of life amid pronounced scarcity. But first we need to ascertain whether the equivalence thesis is true. If it is, then we can work out what to do about the negative impacts of doctors opposing it. In this article, we argue that the equivalence thesis is false. There is a difference between withholding and withdrawing in that there can be instances in which an act of one type would be permissible while an act of the other type would be wrong, even though all other things are equal. We use Heidi Malm's distinction between comparison and conflict cases to show that equivalence proponents and opponents may be talking past one another, with proponents focussing on comparison cases and opponents rightly thinking of conflict cases as well.</p
