See http://en.wikipedia.org/wiki/Guaranteed_minimum_income#Minimum_income_schemes_around_the_world http://en.wikipedia.org/wiki/Guaranteed_minimum_income#Minim.

See http://en.wikipedia.org/wiki/Guaranteed_minimum_income#Minimum_income_schemes_around_the_world http://en.wikipedia.org/wiki/Guaranteed_minimum_income#Minim... for some pointers to schemes which have actually been tried.