Social Choice Theory and the Informational Basis Approach

Kevin Roberts
Nuffield College, University of Oxford


Abstract
For over a quarter of a century, the use of utility information based upon interpersonal 
comparisons has been seen as an escape route from the Arrow Impossibility Theorem.  This
paper critically examines this informational basis approach to social choice.  Even with 
comparability of differences and levels, feasible social choice rules must be insensitive
to a range of distributional issues.  Also, the Pareto principle is not solely to blame 
for the inability to adopt rules combining utility and non-utility information:  if the 
Pareto principle is not invoked then there is no way of combining utility and non-utility 
information in a ranking of states unless levels of utility are comparable; with only level 
comparability, information must be combined in restrictive ways and the notion of giving 
different independent weight to different considerations is ruled out.  If informational 
bases are viewed as the restriction on information that is available, rather than a 
theoretical limit on information, then there exist methods to estimate richer informational 
structures and overcome some of these difficulties.