The valency approach, while very successful in German lexicography and contrastive work, has suffered from continued theoretical frustration. Valency grammarians have sought in vain for an operational criterion that could provide a firm theoretical foundation for their approach by distinguishing valency-bound elements from non-valency-bound elements. This lack of success has led Jacobs (1994) to conclude that valency is not a unified phenomenon but is merely a metaphorical cover term for a number of independent relations.
This article takes issue with Jacobs attack and shows that in scenario constitution a semantic relation, based on Tesnières original drama metaphor, can distinguish prototypical valency cases from prototypical non-valency cases in accordance with applied work. Scenario constitution is a two-valued, non-gradable relation that is indeterminate for a number of cases. It not only gives valency conceptual content but also explains why no sharp distinguishing criterion can be found in principle. The importance of form relations (determination of form features, obligatoriness) is acknowledged for the description of valency bound elements but not for their definition.
Apart from Jacobs work, that of Engel, Schumacher, Heringer, Storrer, Zifonun and others is touched upon.