  We consider the problem where a set of individuals has to classify $m$
objects into $p$ categories and does so by aggregating the individual
classifications. We show that if $m\geq 3$, $m\geq p\geq 2$, and
classifications are fuzzy, that is, objects belong to a category to a certain
degree, then an optimal and independent aggregator rule that satisfies a weak
unanimity condition belongs to the family of Weighted Arithmetic Means. We also
obtain characterization results for $m= p= 2$.
