I think an important part of 'rules' is that the child learns that a rule is reasonable and fair. So for every rule the parent should be able to explain the 'wh

I think an important part of 'rules' is that the child learns that a rule is reasonable and fair. So for every rule the parent should be able to explain the 'why'. That said, rules are very important, not only to give the child an orientation at which it can measure its own actions but also because they can introduce some kind of objectivity into parenting (from the perspective of the child). So rules should always be communicated to the child before they are enforced. Punishing a child for breaking a rule it never heard of before is not fair. Btw. sometimes it can be a good idea to let the child define rules to let it find out how well it can follow its own rules ;-)