"Fuzzy Thinking"
by Bart Kosko
Link: http://www.amazon.co.uk/Fuzzy-Thinking-New-Science-Logic/dp/0006547133/
Reading history and reviews
Finished in 2006
I enjoyed this book but I don't imagine it's really a very good introduction to the subject of "fuzzy logic" (and originally published in 1993, so it's also quite old now), and sometimes the title seemed unintentionally apposite.