Recently New Scientist had a series of articles talking about the limitations of reason. They run from the hackneyed (Rowan Williams talking about how reason doesn't a basis for morality) to neuroscience (consciousness lags behind actual decision making) to the cliched--reason doesn't explain aesthetics, doesn't account for "other ways of knowing", etc.
Consciously used reason is like riding a bicycle with the training wheels--it's what you do till you get the knack. But practice makes perfect, and the way you practice making proper judgements is to apply reason to your decisions. The denigration of reason is like expecting you to play a sport perfectly without ever having practiced. I'm sure that the first time that Tiger Woods swung a golf club, he missed the ball, or knocked it off to the side. Even a natural needs practice. We practice thinking by using reason, by analyzing the roots of our decisions, ferreting out the unexamined and erroneous factors, and replacing these with sound principles. By doing so, we eventually learn to do it "without thinking"--but a lot of thought goes into this end result.
The best analogy I can think of is from programming. When you begin writing a program, you first debug by eye, examining the logic manually to look for errors. The next step is compiling, where the compiler picks out syntax errors, which you must then correct. Yet even then, you run the program in debug mode; the code is festooned with symbols and error checking, which makes it slow, but which allows you to trace the logic and find the errors in your code. Only when it passes all these tests, and functions perfectly, do you compile a release build. The release build is optimized for speed and size, but it is incomprehensible, without symbols or the ability to trace the logic properly. It is unconscious code, no longer available for examination. Reason is the error checker. Once you've debugged your thinking, you can stop thinking about it--you reach your conclusions unconsciously.
While it may be true that reason alone will not lead to a complete system of ethics of aesthetics, it is also certain that the negligence of reason will result in a compacted version of both. It was only when the ideas of the enlightenment encountered the impulse of empathy that slavery and sexism were recognized as untenable and unethical. Or perhaps Rowan Williams would like to return to the primitive ethics of the ancient era, or those of the stone age, when murder was the leading cause of death. This was the product of ethics unleavended by reason. And reason may not be sufficient, in and of itself, for aesthetics, but it was responsible for the science of perspective which resulted in the artistic explosion of the renaissance, and for the ideas which have dominated every school of art from that point forward. I do not hear the anti-rationalists praising the skills of cave painters as the ultimate achievement of the arts. But if you want art without reason, that is what remains.
What I see in the denigration of reason is a culture of mediocrity, and ready-made excuse not to think or strive. I am reminded of the purile sentiments of the Star Wars movies: "Stretch forth with your feelings, use the force." Apparently heeding his own advice, George Lucas achieved new levels of mediocrity in big budget productions, assaulting his fans with wooden characters and dialogue desparately in need of some critical correction. Reason is critical, in both senses of the word--important, and corrosive when applied to nonsense.
But like knowledge, a little reason is a dangerous thing--the problem being not reason itself, but reason that stops and roots itself on what, in a search algorithm, we would refer to as "local minima"; this is a problem encountered when the search is too narrow. In pathing, the AI will get stuck in a dead end. Such a solution appears perfect only because too little critical thinking is applied to it.
I have been compiling a list of over 40 motivations for religious belief. Amongst these is the illusion of certainty, the conviction that you have a simple explanation for everything. I think this one lands in the top five, and it explains not only religions, but all the 'isms', those one-size-fits-all solutions to all the world's problems. None of these work. The influences upon the mind of a single human being include genetics, physical development, childhood and educational influences, culture, fashion, information or the lack thereof, physical states, emotional states, community membership and peer influence, self-interest, fear, and unexamined assumptions--and I'm sure I haven't caught everything here. When considering an entire society, you raise the level of complexity exponentially. No simple algorithm could encompass all that.
And still, even people who pride themselves on being rational fall for such simple-minded transcendalizations. Marxism used to be the opiate of the intellectuals; the flavour of the day is Libertarianism. There is nothing wrong with charity or freedom, just as there is nothing wrong with intuition, love, beauty, or even reason itself. The problem arises when you take any single principle and raise it to the level where you believe nothing else is required.
All have their place, just as reason has its place. But now we seem to be treated to a procession of people who would like to claim that reason isn't needed at all, or that it has done nothing for us. Of course, the argument is inherently contradictory, as you need reason to argue against reason. And invariably, when denigrating reason, there is something else that the critic would like to put in its place--usually faith, or some other, vaguely specified "way of knowing." But none of these ways of knowing actually produce knowledge, and all of them, if one examines them carefully, require the use of reason to train them and clarify them. Without reason, none of them would amount to much.