 Or is she? Once we give up on the 19th century notion that economic value is an objective property of commodities, and embrace instead that value is a function of the subjective preferences of economic agents, the problem with this analysis becomes readily apparent. Economic exchange is only possible precisely because different agents assign different values to the same object. I sell you my old television for $75 because I’ve bought a new set, and to me, the old television is worth less than the $75. You pay the $75 because you just moved into a new place and, to you, the $75 is worth less than the television. Neither of our valuations is the “right” one. Our preferences simply differ, and so it is possible for us to both walk away from the deal believing—correctly!—that we have gotten more than we have given up.