What is the author's purpose in the nonfiction book, Thinking, Fast and Slow?

Kahneman explains that he was compelled to write this book due to new understanding of judgment and decision-making that has been uncovered over the last several details. He has partnered on many projects with psychologist Amos Tversky who was a scholar in decision research. Kahneman attributes a good measure of his motivation for writing this book to Tversky who he met in 1969 when Kahneman asked Tversky to be a guest speaker at the University of Jerusalem.