I am not really very good at summarising books but below are somebody else's words on the book !!
I have really enjoyed this alternative view. I always get the feeling that 'economics' experts' and the like, are slightly wooly and this book does explain why I feel that ! He has filled me with suspicion for bell curves, predicting economic futures and the vested interests and bias' at work.
" The Impact of the Highly Improbable. According to Taleb, high-impact rare events ('Black Swans') are not anything like as rare as we think they are and their effect is so disproportionately large that they effectively drive events in the world.
This may not sound all that provocative, but Taleb's argument is that virtually everybody's view of the world as essentially linear and step-by-step is just an illusion that protects us from understanding that our progress through life is much more random and fragile than we think.
Taleb's outstanding first book, Fooled by Randomness, is about the much greater role of luck in life than is commonly understood. The Black Swan develops this thesis further and shows that rare and unexpected events (what you might think of as a subdivision of luck) drive much of the results in the world.
Since reading Richard Koch's The 80/20 Principle eight or so years ago - after which I began to look at the world through the lens of unequal cause and effect - I have been coming gradually around to Taleb's views. Even so, The Black Swan is difficult to assimilate - and it must seem extremely odd (and itself most improbable) to those who have not had some preparation.
One can see this difficulty in the absolute refusal of modern academic finance to give up theories of how the world works (the bell curve or pattern of 'normal' distribution) that allow them to use complicated mathematics and which are just plain wrong. Taleb thought the Long Term Capital Management debacle in 1998 - in which various Nobel-winning economists proved their (Nobel-winning) ideas did not apply in the real world - would be the end of these dangerously wrong beliefs."