Some conceptions of utility are purely ordinal, not cardinal—consistent preferences expressed in choices (do X instead of Y) can be modeled as an ordering function, without numeric values. Assignment of numeric values to utility is purely a modeling choice, and can lead to incorrect assumptions, like addititivity (which is only valid if choices are fully independent).
The idea of “negative utility” is part of this extension, which is less-well-supported and may or may not make sense in a formal rational analysis. It certainly makes sense in a humanist psychological sense, but combining the two is … difficult.
Some conceptions of utility are purely ordinal, not cardinal—consistent preferences expressed in choices (do X instead of Y) can be modeled as an ordering function, without numeric values. Assignment of numeric values to utility is purely a modeling choice, and can lead to incorrect assumptions, like addititivity (which is only valid if choices are fully independent).
The idea of “negative utility” is part of this extension, which is less-well-supported and may or may not make sense in a formal rational analysis. It certainly makes sense in a humanist psychological sense, but combining the two is … difficult.