A poster on another thread posted a link to this interesting and (to me) convincing piece by John Gray, whose book Straw Dogs argues along similar lines.
www.bbc.co.uk/news/magazine-28341562
Basically he says that human history shows that we can't rely on rationality - humans are naturally emotional creatures prone to cruelty, violence and magical thinking.
I tend to agree with him, though I think he downplays the role of committed and idealistic humans who set up institutions that can make our societies better, if certainly not perfect.
But my question is, where do we go from here? Rationality is unreliable. There may be a kernel of truth in religion and there is certainly a lot to learn from the kinder and more tolerant religious traditions, but there is far too much contradiction between the different religions and sects for me, at least, to take any of the doctrine seriously.
So, how to be a human being? How can we operate, mentally and day-to-day, in the face of the evidence that humans are basically irrational and not very nice?