Utility

The thing about utility is that it's unquantifiable. The thing about utilitarians is that they don't understand that it's a good thing.

Utility being unquantifiable is beneficial to society for several reasons. It can make economic transactions be beneficial to both parties. Consider this example: say that I have a movie on DVD that you like, and that you have a CD by an artist that I like. Now, I've seen this movie and it's meh, ok, but it's nothing special. You, on the other hand, love this movie to death even though it probably stars Dane Cook. However, you recieved the CD as a birthday gift and you aren't really into Coldplay. Should we trade? Absolutely! Congratulations, we both increased our utility.

The fact that we can't quantify utility is what led to the invention of money. Finally, something that we CAN quantify. You can't tell me how many units of happiness a DVD gives you, but you sure as hell know that it's worth 14.95 plus tax. That 14.95 plus tax should, in an economically efficient society, be able to buy you something with the same amount of utility as the DVD.

Side note: Barter is legal in all 50 states.