Enlighten me

I need some help. I've been getting increasingly disturbed at the way in which the Enlightenment gets invoked by the self styled 'hard liberals' as if it amounts to their tablets of stone. Something didn't seem to be adding up to me when they waxed lyrical about the Enlightenment legacy of rationality, secularism, belief in progress, the rule of law and the basis of all we know and love in western democracy and individual human rights.

Then I began bumping into the subject with Muslim intellectuals who were acutely aware of how this legacy was being used (implicitly or explicitly) against Islam. It was as if the debate had shifted from the Reformation - why hasn't Islam had one? (it dawned on such questioners that a)the Christian Reformation led to several centuries of appalling bloodshed and b)there's a good argument that Wahabi Islam is precisely Islam's reformation) - to another tack: why hasn't Islam had an Enlightenment?)

These Muslims then argue that the Enlightenment was a process of European definition in the face of the Ottoman Empire; it was shaped in opposition to Islam and hence has an inbuilt anti-Islamic bias. Montesquieu's 'Persian Letters' is a good example of this.

Hence I was gripped by the exchange between two philosophers, Eric Bronner and Jonathan Ree at the Institute of Public Policy Research/New Humanist conference last week on faith and politics. Bronner kicked off the debate by arguing that the Enlightenment is at the heart of all democracy. It forms the basis of freedom and human rights, for example its views on torture. It argued that we temper our worst tendencies through reason. It was not against religion, but against fanaticism, and argued that religion should be kept in the private sphere. He cited Comte as accepting religion but within the bounds of reason (I'm not sure how Comte was going to square that). He concluded by saying we need to pick up the Enlightenment legacy and adapt it.

Ree countered by saying the Enlightenment had never happened - or at least certainly not in the shape we think it did. It was a retrospective creation in the nineteenth century designed to make the eighteenth century look silly - the gist was that excessive pride in human rationality was a story which had ended in tears in the brutal terror of the French Revolution. Ree pointed out that all the great thinkers attributed to the Enlightenment such as Hume, Locke, Kant were actually religious believers and none of them believed in progress.

The bit which most intrigues me is whether a new understanding about rationality emerged in the eighteenth century and if so, how was it then positioned vis a vis religious belief? Since then, we've had Freud, Foucault and Nietzsche - all of whom have contributed to the understanding that we are profoundly irrational and that rationality is a social construction - a way of reasoning which we believe to be objective, but never can be.

I'm no philosopher - hence the need for help - but I have a few questions: a) why do people think an understanding of rationality which is over 200 years old is useful now? As Ree said to Bronner why do we want to resurrect bits of our intellectual history?

And b) more generally, what is it about the Enlightenment that people are now taking it off the shelf to polish up and put forward as their political and intellectual credentials?