In September 2000, the United Nations Millennium Development Goals rallied the international community behind a shared vision. The MDGs, which expire in 2015, signaled a new era of global cooperation. They triggered real progress in terms of lifting millions of people out of extreme poverty, improving health and access to education, and empowering women.

The eight original MDGs, which include reducing child mortality and achieving universal primary education, are lauded for their simplicity and measurability. They took an abstract, outsize challenge and distilled it into achievable ends. But as Albert Einstein loved to say, "Not everything that counts can be counted, and not everything that can be counted counts."

Today, it is important that we do not become trapped by what worked in the past. To succeed, the post-2015 agenda must break the original mold. It must be grounded in a fuller narrative about how development occurs - a narrative that must account for complex issues such as migration - otherwise the global development agenda could lose its relevance and thus its grip on stakeholders.