However, other philosophers have pointed out flaws with the idea (or at least with simplistic interpretations of it):
- Suppose that a ruler controls a weapon capable of instantly and painlessly destroying the human race. Now it is empirically certain that there would be some suffering before all those alive on any proposed destruction day were to die in the natural course of events. Consequently the use of the weapon is bound to diminish suffering, and would be the ruler's duty on NU grounds.
- Negative utilitarianism would seem to call for the destruction of the world even if only to avoid the pain of a pinprick.
I guess what I'm getting at is that (a) we should try to reduce harm when it is actually present or reasonably foreseeable, as opposed to merely potential, and (b) reducing harm is not an end in itself, but part of the goal of ensuring that as many people as possible have maximum opportunity to live full, rich lives and exercise their autonomy as individuals.
If I decide to kill Alice (albeit instantly and painlessly) this morning to guard against the possibility that she might suffer a pinprick later today, I am making a decision that is not mine to make. I am infringing on Alice's autonomy in the biggest possible way, and taking away the possibility that she will experience good as well as harm. In short, I am inflicting harm on her.
The problem that positive utilitarianism has in common with negative utilitarianism is that if I go the other way and try to maximize Alice's happiness, I once again run the risk of overriding her autonomy. My idea of what would maximize her happiness may not correspond to hers, and the problems are compounded exponentially if I try to maximize the happiness of an entire society!
So if I were to restate my idea, I would give greater emphasis to the positive value of respecting people's autonomy. Co-operate with people, reduce harm to them when you reasonably can, but don't blindly follow some principle or you will probably do more harm than good!