See my response above, but this suffers the same problem. Economics people talk about "utility" as a single number, when in reality its a multi-dimensional (perhaps infinitely dimensional) number. Because it depends on a multitude of independent variables (age, health, experience, intelligence, expertise, efficiency, relationships, persausion / charisma, etc.), it can never be simplified. This also makes it impossible to compare two utility values, because there's no way to strictly order variables in many dimensions (without arbitrary reduction in complexity that loses information like calling "cost" or "hours worked" the primary axis and sorting on that).