Sometimes it's rather puzzling why people should believe what they do. In Descarte's Baby: How Child Development explains what makes us Human
Paul Bloom looks at how we come by some of our thoughts and beliefs. He starts off by examining how children come to recognise the existence of other minds, followed by a look at how we make sense of objects around us - recognising whether or not they seem to be there for a purpose. There is also a discussion of how we get our sense of morality, and at when and why we might experience disgust. The book concludes with a look at our spiritual beliefs.
The most insightful chapter though is one on Art. Why should we ascribe great value to certain objects just because we are told that they are works of art. This is one of the most puzzling questions, but Bloom succeeds in finding a reasonable explanation - philosophy of art is clearly his area of expertise. I felt that the rest of the book didn't offer the same sort of insights, either from a philosophical or a child development point of view. But Bloom is an experienced writer, and puts forward his arguments in a very readable way, so if you're interested in why we believe what we do, and in particular in the way we think about art, then you should take a look at this book.