Should aid continue to flow to middle-income countries, or should the world’s poorest countries receive a greater share? It is a debate that has intensified since world leaders set the millennium development goals (MDGs) 15 years ago, during which time more than 30 countries have moved from low- to middle-income status. MDG8, which aims to “develop a global partnership for development”, includes a target to increase aid to the world’s 48 least developed countries. Some campaigners argue this should be the priority, while others insist the world would fail most of the world’s poor if aid to middle-income countries was cut. The Guardians has asked two experts to share their thoughts on where the priorities should lie. Read their answers here.