David7204 wrote...
Then why on a Earth would someone pretend to have a second set of principles simply to throw away and make way for the 'real' principles any time a slightly difficult situation rears its head? That seems to be quite pointless and ridiculous.
Actually, John Stuart Mill proposes a system very much like this in
Utilitarianism. Under most circumstances, you follow a system of secondary principles (which consist of generalities like "Keep promises," "Do not harm others," etc.); only when these secondary principles are in conflict do you apply the over-arching Principle of Utility directly. The reason why you didn't just apply that principle to every situation, according to Mill, was that utilitarian calculation was time-consuming, and people are generally very bad at it. Thus, the general good would actually be promoted more if people relied on secondary principles most of the time. Henry Sidgwick took this line of thinking even further, suggesting that even though he himself took utilitarianism to be true, it would probably be best if most folk weren't utilitarians.