When it comes to the suffering of the extremely poor, people across the political spectrum see a moral argument for doing something to alleviate the misery.
Just 100 years ago, cities like London and New York resembled some of the most disease-ridden cities in today's developing world. From past experience, we can draw on our knowledge and skills to help transform such environments.
Some see eliminating poverty — and more specifically improving health — as defending fundamental human rights and bringing fairness and equity to society.
Others with a more spiritual outlook rely on their religious beliefs to help guide their thinking.