I have recently revised my views in light of Michael Huemer's latest book, which I found convincing (, despite my initial reluctance to accept many of his findings).[1] It takes at least a book to explain his reasoning (which rightfully separates political legitimacy and political obligation from each other and independent moral obligations), and I won't bore you with poor paraphrasing here.

[1] http://www.palgrave.com/page/detail/the-problem-of-political...