You could have a method on a class that uses it's own fields to do some calculation. So, although it does have access to the fields on the class, it takes no ar

You could have a method on a class that uses it's own fields to do some calculation. So, although it does have access to the fields on the class, it takes no arguments and has no side effects. You could certainly argue that a class's fields are a form of input arguments to a method, and I would agree - which is why another good rule of thumb is to not have too many of those either! Obviously, it's a balance, so none of the rules can be taken without context to the situation - they are all just smells that you should "back away from" if you're finding yourself breaking any given rule too much.