Most of my open-minded friends read a lot. Most of my non-open-minded friends don't. It makes sense that the more you read, the more likely you are to be challenged by new ideas and that your commitment to your own ideas will weaken. Reading also frees you from everyday life and shows you the variety and richness of life. Therefore, reading makes people open-minded.
 Some people read a lot of books, and every book they read makes sense. Different reasons always fight in their head, and they almost become crazy most strongly undermines the conclusion above.