A few years ago the author published 'The Master and his Emissary' a magisterial essay on the different thinking styles in the two hemispheres of the brain. A great and challenging book but heavy going for the non-specialist reader - 'Another damned thick, square book, eh Mr Gibbon!' as a former member of the royal family said of the 'Decline and Fall'. So McGilchrist has re-stated his arguments in a much more readable way. Because the ideas in it are important, they deserve the widest consideration, and this book is a long step down that path - I would even describe it as enjoyable.
The left and right hemispheres of the brain work together in our thinking processes, but they are very different in the way they go about it. The details are too many and too complex for this review. However as a great simplification, the left is reductionist and concerned with hard logic, the right holistic in bent and concerned with the believable inference. McGilchrist thinks that contemporary culture overvalues the contribution of the left at the expense of the right.
He makes what I think are errors, in particular seeming to believe that science is necessarily reductionist. It was, once upon a time, but not now. Statistical mechanics, thermodynamics, information theory and relativity theory are holistic. Others are a mix, like theoretical biology. But this is just to name the few of which I have some knowledge, matters of detail, easily corrected. The overall argument is powerful and would have profound implications. And is McGilchrist right? Gentle reader, you must judge.