AleutianTexan

I was in a current events thread and this came up as a core prior question to the issue of a police shooting. However, the question in a vacuum is a good one and I was directed to create this thread. 

Classic liberal thought, from what I understand, is that a government is only legitimate if it does its job in protecting liberty/property, and a tyrannical government would, therefore, be ethically able to be brought down. The counter, however, would be the argument that the government knows what is best or that reforming institutions is better than radical revolution. This is a general starting point, but I want to see what other people have to say about it.