[keane]

> Utilitarianism -- and many others -- are equally possible.

You misunderstand the dichotomy. This is not about what we can do, humans can delude themselves all the time. The question is about what is logically consistent.

"That which can be asserted without evidence, can be dismissed without evidence" applies in a purely natural universe, which means that if there is no God, we can dismiss Utilitarianism (and all the others) as there is no evidence for it. Only if the universe is supernatural (if God exists) do things change.