The Difference Between Utility and Utility

Re­cently I ar­gued that the economist’s util­ity func­tion and the ethi­cist’s util­ity func­tion are not the same. The nut­shell ar­gu­ment is that they are cre­ated for differ­ent pur­poses—one is an at­tempt to de­scribe the ac­tions we ac­tu­ally take and the other is an at­tempt to sum­ma­rize our true val­ues (i.e., what we should do). I just ran across a some­what older post over at Black Belt Bayesian ar­gu­ing this very point. Ex­cerpt:

Eco­nomics (of the neo­clas­si­cal kind) mod­els con­sumers and other eco­nomic ac­tors as such util­ity max­i­miz­ers… Utility is not some­thing you can ex­pe­rience. It’s just a math­e­mat­i­cal con­struct used to de­scribe the op­ti­miza­tion struc­ture in your be­hav­ior...

Con­se­quen­tial­ist ethics says an act is right if its con­se­quences are good. Mo­ral be­hav­ior here amounts to be­ing a util­ity max­i­mizer. What’s “util­ity”? It’s what­ever a moral agent is sup­posed to strive to­ward. Ben­tham’s origi­nal util­i­tar­i­anism said util­ity was plea­sure minus pain; nowa­days any con­se­quen­tal­ist the­ory tends to be called “util­i­tar­ian” if it says you should max­i­mize some mea­sure of welfare, summed over all in­di­vi­d­u­als… Take note: not all util­ity max­i­miz­ers are util­i­tar­i­ans.

There’s no nec­es­sary con­nec­tion be­tween these two kinds of util­ity other than that they use the same math. It’s pos­si­ble to make up a util­i­tar­ian the­ory where eth­i­cal util­ity is the sum of ev­ery­one’s eco­nomic util­ity (cal­ibrated some­how), but this is just one of many pos­si­bil­ities. Any­one try­ing to rea­son about one kind of util­ity through the other is on shaky ground.