The crux of the argument (and most of the book for that matter) is that you want to avoid mutability whenever possible. Adding setters for every field by default means mutability is the default mode for your application. Adding getters for every field by default means you lose any advantages of encapsulation. At one time, Java Beans were a heavily marketed pattern by Sun. Joshua Bloch came along and said "hey, this is a bad pattern" (and maybe others, but he's the one I always think of).