At the level of tax design, the answer to this question is clear and positive. It would be easy, for example, to draft the international treaty and the national legislation required to implement Thomas Piketty’s (2014) proposal for a global tax on wealth. The obstacles to acceptance and implementation of those proposals are merely political – but at the same time they are formidable. There has been a steady, worldwide movement away from wealth taxes of any kind in recent decades, and the many previous calls for international cooperation to establish some kind of global tax have failed (Bird, 2015). Political realism suggests that we start somewhere else.