Valency-decreasing operations in a valency-increasing language?

Abstract This paper surveys valency-changing operations in West Circassian (Adyghe), a polysynthetic language of the Northwest Caucasian family. This language has an amazing number of means to increase valency, which include various kinds of applicativization and causativization. In this paper we also present processes which may look valency-decreasing and argue that they do not necessarily remove arguments, even though some of them change transitivity. This implies, in particular, the need for distinguishing between valency change and transitivity change.