Munthe et al1 argue for an asymmetry between positive and negative dynamics that justifies a new sustainability principle among the operational principles for ethical healthcare resource allocation. The purported asymmetry is that while positive dynamics are ‘taken into account in present applications of the operational principles…, negative dynamics are not’.1 Positive dynamics occur when allocations in the present lead to there being more healthcare resources per health need in the future (than are available in the present), whereas negative dynamics occur when present allocations lead to there being less future healthcare resources per health need.i Munthe et al1 are correct that we have ethical reason to reduce negative dynamics—all other things being equal, having less future healthcare resources per health need is worse than having more. Furthermore, this ethical reason ought to be accounted for by operational principles. However, using current examples…