Wikipedia calls it value-pluralism and offers an actual example:
An example of value-pluralism is the idea that the moral life of a nun is incompatible with that of a mother, yet there is no purely rational measure of which is preferable. Hence, moral decisions often require radical preferences with no rational calculus to determine which alternative is to be selected.What strikes me in the above is the move from "no purely rational measure" to "no rational calculus". What gets dropped out is the "purely". Is that perhaps an important dropped term? Really, it makes me wonder what the "purely" is doing there in the first place. I suspect it's doing the work of separating reason from the person's own individual human needs and wants.
I see it as the Sound Of Music problem. The Mother Superior is happy as a nun. Maria will not be.
She happens to be a bad fit
for happiness in it.