Well, you can argue for whatever you think as long as you don't question the fundamental context in which, siyasa, fiqh, maslaha, 'democracy', state, etc operate or determined, i.e. as long as you don't question how the socio-economic structure relates to social justice and law, ownership and social relations and powers. Ms Landes, correctly referred to the "Islamic governments" of the pre-colonial era, but ignored the global entrenchment of the capitalist system in today's "Muslim societies". How can one question the euro centric concepts without questioning capitalist "democracy"? 
It's the limit of the liberal thinking.

"How to create an Islamic government — not an Islamic state"