One of the most commonplace worries about humanitarian intervention relates to the perverse incentives that it might create, or the adverse reactions that it might provoke. For instance, it is sometimes said that by weakening the norm of sovereignty humanitarian intervention can encourage unscrupulous states to wage aggressive wars of self-interest using human rights as a pretense. It is feared, in other words, that humanitarian intervention—even when it has the purest motives—might ultimately do more harm than good by inciting unwanted (...) reactions from other states or substate groups. I will refer to these kinds of knock-on effects as the mediated consequences of intervention. They are brought about via the interceding agency of parties other than the intervener. It is generally assumed that when judging the proportionality of a humanitarian intervention, these consequences must be factored into the equation. If an intervention is expected to provoke adverse reactions the accumulated costs of which will outweigh the benefits that the intervention will deliver, then the intervention is thought to be disproportional and, therefore, unjustified. I want to challenge this assumption. I begin by considering what the principle of proportionality can reasonably demand of rebels who are defending their own basic rights against an oppressive government. I argue that a rebellion in such circumstances cannot plausibly be rendered impermissible solely by the expectation of negative mediated consequences, even when those consequences outweigh the anticipated benefits of the rebellion. This would seem to imply that rebels may discount mediated consequence from the proportionality calculus. But if this is so, do we have sound reasons for withholding the same prerogative from humanitarian interveners pursuing similar ends and using similar means? Can we justify asymmetric standards of proportionality? (shrink)