The above link is to an interesting Article by the Quilliam Foundation on why the idea of a Caliphate is delusional. These paragraphs stood out to me, substitute "JW's" for "Islamists" and see what you think.
" The facts of history, however, are largely irrelevant to modern Islamists because theirs is a struggle and a cause that is characterized by the meaning it gives to their lives and the excuses it offers to avoid introspection. In other words, it’s too good to be spoiled by the facts and alternative perspectives are deemed an irritant, getting in the way of a comforting and binary understanding of the world.
It is for these reasons that most Islamists, in my experience, resort to name-calling and playing the man rather than the ball when challenged. A tribal mindset in which any criticism of their politics is deemed an attack on the faith and their entire identity kicks in and enables them to pull the shutters down. In such a climate rational debate is difficult."