 Contractualists might reply that principles of aid presuppose some background set of entitlements, guaranteeing me the free use of my own resources. This raises two problems. The first is that, from the fact that I own something, it does not follow that I do not have an obligation to give it away. The most that might follow is that others may not force me to do so. The second problem is that, if our overall theory is Contractualist, then the property rights themselves must be given a Contractualist justification. We need a system of property rights no-one can reasonably reject. Any system where property rights are very unequally distributed will be rejected by those who miss out.