Luis Cabrera 
Political Theory of Global Justice [PDF ebook] 
A Cosmopolitan Case for the World State

Could global government be the answer to global poverty and starvation?
Cosmopolitan thinkers challenge the widely held belief that we owe more to our co-citizens than to those in other countries. This book offers a moral argument for world government, claiming that not only do we have strong obligations to people elsewhere, but that accountable integration among nation-states will help ensure that all persons can lead a decent life.
Cabrera considers both the views of those political philosophers who say we have much stronger obligations to help our co-citizens than foreigners and those cosmopolitans who say our duties are equally strong to each but resist restructuring.