that of the least advantaged and to further their long-term prospects in the
best manner consistent with the equal liberties and fair opportunity. It
seems that the policies in the justice of which we have the greatest
confidence do at least tend in this direction in the sense that this sector of
society would be worse off should they be curtailed.
These policies are
just throughout even if they are not perfectly just. The difference princi-
ple can therefore be interpreted as a reasonable extension of the political
convention of a democracy once we face up to the necessity of adopting a
reasonably complete conception of justice.
In noting that the mixed conceptions have intuitionistic features, I do
not mean that this fact is a decisive objection to them. As I have already
observed (§7), such combinations of principles are certainly of great
practical value. There is no question but that these conceptions identify
plausible standards by reference to which policies may be appraised, and
given the appropriate background institutions,
they may guide us to sound
conclusions. For example, a person who accepts the mixed conception to
maximize average well-being less some fraction (or multiple) of the
standard deviation will presumably favor fair equality of opportunity, for
it seems that having more equal chances for all both raises the average
(via increases in efficiency) and decreases inequality. In this instance the
substitute for the difference principle supports the other part of the sec-
ond principle. Furthermore it is evident
that at some point we cannot
avoid relying upon our intuitive judgments. The difficulty with the mixed
conceptions is that they may resort to these judgments too soon and fail to
define a clear alternative to the difference principle. In the absence of a
procedure for assigning the appropriate weights (or parameters), it is
possible that the balance is actually determined by the principles of jus-
tice, unless of course these principles yield conclusions that we cannot
accept. Should this happen, then some mixed conception despite its ap-
peal to intuition may be preferable, especially if
its use helps to introduce
order and agreement into our considered convictions.
Another consideration favoring the difference principle is the com-
parative ease with which it can be interpreted and applied. Indeed to
some, part of the attractiveness of mixed criteria is that they are a way to
avoid the relatively sharp demands of the difference principle. It is fairly
straightforward to ascertain what things will advance the interests of the
least favored. This group can be identified by its index of primary goods,
and policy questions can be settled by asking how the relevant repre-
sentative man suitably situated would choose. But to the extent that the
principle
of utility is given a role, the vagueness in the idea of average (or
281
49. Comparison with Mixed Conceptions
total) well-being is troublesome. It is necessary to arrive at some estimate
of utility functions for different representative persons and to set up an
interpersonal correspondence between them, and so on. The problems in
doing this are so great and the approximations are so rough that deeply
conflicting opinions may seem equally plausible to different persons.
Some may claim that the gains of one group outweigh the losses of
another, while others may deny it. No one can say what underlying
principles account for these differences or how they can be resolved. It is
easier for those with the stronger social positions
to advance their inter-
ests unjustly without being shown to be clearly out of bounds. Of course
all this is obvious, and it has always been recognized that ethical princi-
ples are vague. Nevertheless they are not all equally imprecise, and the
two principles of justice have an advantage in the greater clarity of their
demands and in what needs to be done to satisfy them.
It might be thought that the vagueness of the principle of utility can be
overcome by a better account of how to measure and to aggregate well-
being. I do not wish to stress these much
discussed technical problems,
since the more important objections to utilitarianism are at another level.
But a brief mention of these matters will clarify the contract doctrine.
Now there are several ways of establishing an interpersonal measure of
utility. One of these (going back at least to Edgeworth) is to suppose that
an individual is able to distinguish only a finite number of utility levels.
44
A person is said to be indifferent between alternatives that belong to the
same discrimination level, and the cardinal measure of the utility differ-
ence between any two alternatives is defined by the number of distin-
guishable levels that separate them. The cardinal scale that results is
unique, as it must be, up to a positive linear transformation. To set up a
measure between persons one might assume
that the difference between
adjacent levels is the same for all individuals and the same between all
levels. With this interpersonal correspondence rule the calculations are
extremely simple. In comparing alternatives we ascertain the number of
levels between them for each individual and then sum, taking account of
the pluses and minuses.
This conception of cardinal utility suffers from well-known difficul-
ties. Leaving aside the obvious practical problems and the fact that the
detection of a person’s discrimination levels depends upon the alterna-
tives actually available, it seems impossible to
justify the assumption that
44. See A. K. Sen,
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