Left-wing economists generally argue that governments need tax revenue to cover debts and contingencies, and that paying to fund a welfare state is an obligation of social responsibility. Another argument is that tax competition is a zero-sum game. Right-wing economists argue that tax competition means that taxpayers can vote with their feet, choosing the region with the most efficient delivery of governmental services. This makes the tax base of a state volitional because the taxpayer can avoid tax by renouncing citizenship or emigrating and thereby changing tax residence.