For better or for worse, one of the most prominent measures of wealthy countries’ fulfilment of their responsibilities towards the global poor is how much aid they provide. For several decades donor and recipient countries have engaged in heated debates over what should and should not be counted under the official definition of aid. Contentious cases currently classed as aid include debt relief, initial costs of refugee resettlement in donor countries, and funding to address climate change.

In this paper I argue that, despite its limitations, the current approach to defining aid (based on the developmental purpose of the funding rather than the moral reasons giving rise to the funding) helps to constrain some of the more blatantly self-interested aid practices while respecting the diversity of legitimate reasons that may motivate citizens to support aid. I assess the claim that funding provided on the basis of a responsibility to remedy or prevent one’s contribution to harm (climate finance being the most prominent example) is incompatible with the purpose of aid. I argue that the element of harm alone should rarely render funding ineligible to count as aid unless it is the only plausible reason for providing the funding. Moreover, over-emphasizing the distinction between aid and harm-based funding may be counterproductive in downplaying the stringency of widely accepted moral reasons for providing aid. In the case of climate finance, the more pressing concern is that the large scale of funding required could swamp funding for existing development needs. Addressing this concern may not require excising climate finance from aid altogether.