This article deals with hierarchies of operators. In particular, we wi
ll analyze the problem of amalgamating individual opinions into a sing
le group opinion, based upon hierarchical intensity aggregation rules.
Our main goal is to decide whether hierarchical amalgamations are sup
ported from an ethical and rational point of view. We will consider tw
o different hierarchical procedures: cover-based hierarchical aggregat
ions and ordered hierarchical aggregations, focusing here our attentio
n to ordered hierarchical aggregations of OWA operators. In particular
, we will obtain that basic key properties propagate under both hierar
chical amalgamation rules, in the sense that the procedure itself will
verify such properties whenever they are assumed for every partial am
algamation defining such a hierarchical procedure. (C) 1994 John Wiley
& Sons, Inc.