There are far fewer well-defined mathematical relations and operations on the set of "utilities" (aka "utility values", although the word 'value' is misleading since it suggests a number) than most self-stated utilitarians routinely use; for example, multiplying utilities by a scalar makes no sense, the sum of two utilities can only be defined under very strict conditions, and comparing two utilities under only slightly less strict ones.

Consequently, from a rigorous point of view utilitarianism makes very little sense and is in no way intellectually compelling. Most utilitarians satisfy themselves with a naive approach that allows it to build an internally consistent rule set, much in the same way as theology or classical physics. But the "utilities" they talk about have lost most of their connection to reality - to subjects' preferences/happiness - and more closely resemble an imaginary karma score.