Is rule utilitarianism a better form of ethical decision making than act utilitarianism?

The decision rule with act utilitarianism is ‘perform the action that results in the maximum sum of utility from those available when making the decision’. By contrast rule utilitarianism offers the revised decision rule, ‘Perform the action that belongs to the set of rules, that if followed in all circumstances, would result in the most utility’. The supposed attraction of rule utilitarianism is that allows us to avoid actions that we have a natural aversion to, despite the fact they maximise immediate utility. For instance, a carer might steal a prized ornament from a blind old lady. The ornament normally sits out of the old lady’s reach, so she doesn’t know that it’s been stolen. Using an act utilitarian decision rule, the carer is morally justified in his action – he gets the benefit of the ornament to sell, whilst the lady doesn’t know its been taken. This however seems intuitively wrong. Rule utilitarianism offers the chance of reconciling morality with our intuitions; if everyone stole from eachother, there would be a lot less trust in the world, and therefore less utility. As such a rule such as “never steal” might be advisable, and as a result, stealing from the lady would be condemned by a rule utilitarian. However, we might think of situations where the cleaner’s action doesn’t undermine trust. If nobody finds out, and the cleaner instead of arousing suspicion by displaying the ornament in his house, gives it to a charity shop, it would seem wrong to say that the cleaner is harming overall utility, by breaking the rule “don’t steal”, because the reason for this rule – the breaking of trust – doesn’t apply. We could in fact think of a rule that would maximise utility better; “don’t steal, unless there’s no chance that your actions undermine trust”. Given rule utilitarians are committed to the rule that best maximises utility this rule should be selected over the simpler “don’t steal”, and so the carer’s theft remains justified. Our intuitions therefore still aren’t satisfied. We can present a more general utility maximising rule; “Perform the action belonging to rule X, unless breaking rule X leads to greater utility”. This decision rule is essentially that of act utilitarianism – perform whatever action leads to utility maximisation in a given situation. As such we can see that rule utilitarianism, if followed through rigidly, degenerates to act utilitarianism. Therefore, rule utilitarianism isn’t a better form of ethical decision making than act utilitarianism.