They have to. The psychology of what it feels like to learn something from a book is going to be the same whether or not the things the book says are actually true. The psychology of what it feels like to believe the things your teacher tells you and your peers repeat is going to be the same whether or not the things your teacher says are true. You can't just trust the book or the teacher, you have to use whatever other information you have (from observation and experience, from other books, from other teachers) about the reliability of the processes that produced the book, the reliability of your teacher to have done this same kind of thinking.