Utilitarianism first rests on four more-or-less scientific principles:
None of these scientific principles entail any particular ethical system. Utilitarianism thus must add an ethical ideology to these principles.
- People directly experience "happiness" and "suffering"; they're hard to define precisely, but we know them when we feel them. Happiness is intrinsically good, and suffering is intrinsically bad.
- People are goal-seeking, which differs from other possible high-level cognitive strategies such as rule-following; (what Daniel Dennett calls sphexishness).
- People generally create and act on the goal of maximizing their own happiness and minimizing their own suffering.
- People have evolved to be social, and we have evolved the tendency to feel our own happiness when (some) others are happy, and feel our own suffering when (some) others suffer.
Utilitarianism does not describe how the world actually is. It is a framework that people chooses or does not choose to evaluate their actions. The "reductionism" just happens to be part of the theory; as a proponent of utilitarianism, I would not say that utilitarianism is true because it is reductionist. (Indeed, I would not say that utilitarianism is true. Full stop.) Reductionism just serves to make the theory easier to use.I have no response except simply that I agree.
The idea, however, that we know physics is true, that it really describes the world, because it is reductionist is very philosophically problematic. There's no denying that reductionism is a really useful tool in physics, but the connection between reductionism and truth seems very hard to justify.