Our guest this week is Rick Aubry, a leading American social innovator. He established Rubicon Programs to support homeless people and people with mental health issues in finding work and somewhere to live; his latest venture, New Foundry Ventures, is a laboratory that helps other social enterprises who tackling poverty and inequality in the US to scale. Rick is also training the next generation of social entrepreneurs through his work as a professor of social entrepreneurship at Tulane University.In his conversation with Mel, Rick talks about why he thinks that reforming tax is one of the ways we can shape a fairer economic system, his thoughts on the tax versus philanthropy debate, how 'ok' for hundreds of millions is preferable to 'perfect' for tens of thousands - and much more.