I'm a student taking a course in political theory, and I regularly use this book. I don't know where I'd be without it! Split into two halves, the first written by Smart argues the case for utilitarianism. Covering justic, rule and act utilitarianism, average and total happiness and hedonistic and non-hedonistic utilitarianism, it is a comprehensive introduction to the topic. Williams's critique in the second half is a classic - he argues against utilitarianism for reasons of negative responsibility, Integrity and social choice. This is the book in which he gives the stories of Jim and the Indians and George the chemical scientist, both of which are now included in any discussion on utilitarianism. This book is referred to everywhere. It's easy to read, insightful and it's not too big to be scared by! It's a must have reference for anyone writing, reading or talking about utilitarianism.