Thinking and Deciding

UTILITARIANISM AS A NORMATIVE MODEL 401
dividuals. For example, we could ask such (outlandish, but meaningful) questions
as, “Would you accept an hour a day of 100-volt electric shock for a year in order
to prevent the Mona Lisa from being defaced?” (We ask this of a person who may
well never see the Mona Lisa but who has a personal goal of preserving original art
works.) In this way, we could determine the strength of goals that do not involve experiences.
If we knew as well the psychological determinants of aversion to electric
shock, the problem of interpersonal comparison is in principle solved.
When we make interpersonal comparisons, we accept a great deal of error. Surely
many factors affect people’s tolerance for pain, their desire to live, their desire for
material comfort, and so on, and we are not aware of all of these factors. Once
again, the acceptance of error is not an argument that the enterprise is theoretically
impossible or that there is no truth of the matter.
The problem of error led many economists to reject the possibility of interpersonal
comparison. Robbins (1938), for example, cites “the story of how an Indian
official had attempted to explain to a high-caste Brahmin the sanctions of the Benthamite
system. ‘But that,’ said the Brahmin, ‘cannot possibly be right. I am ten
times as capable of happiness as that untouchable over there.’ ” Robins goes on, “I
had no sympathy with the Brahmin. But I could not escape the conviction that, if
I chose to regard men as equally capable of satisfaction and he to regard them as
differing according to a hierarchical schedule, the difference between us was not one
which could be resolved by the same methods of demonstration as were available in
other fields of social judgment.”
Anyone’s estimate of the tradeoff between your utilities and mine could well be
off by a factor of ten. But, crucially, it could be off either way. In making decisions
between the Brahmin and the untouchable, we might just as easily conclude that
the untouchable is more sensitive (because the Brahmin is jaded, etc.). Uncertainty
about the strengths of goals is just one form of uncertainty about the state of the
world. If we follow expected-utility theory, we will made decisions according to our
expectation. Although we can be wrong, we can do no better. If our expectations are
informed, as I have argued they are, the problem of error is not a decisive objection
no matter how great the possible error. For many purposes, we simply assume that
people are alike in their utilities. When we make choices that affect life and death
— such as choices about how much to spend on medical technology — we do not
attempt to determine which of two patients has a greater desire to live.
Utilitarianism and expected utility
Utilitarianism is closely related to expected-utility theory (Chapter 10). When a
group of people all face the same decision, then the two models clearly dictate the
same choice. For example, suppose each of 1,000 people faces a .2 probability of
some disease without vaccination, but the vaccine causes an equally serious disease
with a probability of .1. The best decision for each person is to get the vaccine. If
everyone gets the vaccine, then we expect that 100 will get the disease caused by the
vaccine, instead of 200 getting the other disease.