produce a social choice that perfectly represents the constituent individual
choices.
Arrow’s Impossibility Theorem
Study of social choice by mathematicians and political scientists has tried to
show how, if at all, a social choice can be made which is squarely based on,
or directly derived from, the aggregated preferences of individual members of
that society. If it can be, the social choice is seen as legitimate because it
represents the wishes of a majority of individual members.
In fact, research suggests that such a choice is not possible because society as
a whole is different from the sum of the individuals, the parts that make up the
whole. While this research is based on complex mathematics, it is easy enough
to state the major finding of this research that is relevant here. This finding is
derived from impossibility theorem of Kenneth Arrow (b 1921)
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and the
research of Amartya Sen (b 1933).
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This research makes certain
assumptions. For example, no member of the choosing group (voters or
legislators) can dictate the outcome, and the ensuing social choice will satisfy a
given principle of optimality. Once these and other proper assumptions are
made, it is just not possible to derive a representative social choice (called a
social welfare function) that is based on or derived from the preferences of
individual members. To this extent the proposed model for making and
interpreting law is, in itself, not fully rational.
Social Interaction
Any attempt to amalgamate individual choices must also involve social
interaction. This very process of interaction may thwart representative
aggregation by producing outcomes that differ from the original intentions of
the purposive individuals who make up the social system. Electoral choice is a
pertinent example. It is not just a decision by individual voters. Instead it is
made in the political process involving organisations such as political parties,
and behaviour such as electioneering, both of which may significantly influence
individuals’ choices. Hence the preference that they start out with may be
altered during the electoral process leading up to their exercising that
preference at the ballot box.
Division Between Individual and Social
The notion of numerous individual choices being amalgamated to become a
social choice assumes that there exists a clear division between the individual
and the social; specifically it presupposes that the choice is entirely and purely
the work of the individual unaffected by their social setting. In truth, “social
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KJ Arrow Social Choice and Individual Values (1951)
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Sen (1970). See also Kamesar (1997).
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