Can an Impossible Action Still Be a Duty?

“Ought implies can” is an appealing moral principle. If a person simply cannot perform an action, saying that they still have an immediate duty to perform it can look like a command disguised as a judgement. Kant’s practical philosophy is often used to support this direction: moral requirements are connected to an agent’s practical freedom rather than to absolutely impossible conduct. Yet the familiar slogan is not the whole of Kant’s ethics, and contemporary philosophers still dispute what “can” means: physical possibility, a reasonable opportunity, or success under an appropriate effort.

Suppose you promise to deliver medicine to a neighbour, but a storm brings down a tree and blocks the only road. Insisting that you must still appear at the door on time makes little sense, because direct performance is no longer possible. The obligation does not simply evaporate, however. You may still be able to contact your neighbour, arrange another delivery and explain the delay. If you deliberately ignored a foreseeable risk that you should have planned for, your earlier fault is not erased by your present inability.

My view is that the principle should limit what must be completed now, without automatically removing questions about why performance became impossible or what can still be done next. Genuine inability differs from unwillingness, inconvenience or a merely higher cost. When the original duty cannot be fulfilled, duties to explain, repair and prevent a recurrence may arise. Morality does not demand miracles, but it does ask how we respond to limits.

https://iep.utm.edu/re-bo-ag/
https://iep.utm.edu/kantview/