Economy of Expression as a principle of syntax

The purpose of a grammatical theory is to specify the mechanisms and principles that can characterize the relations of acceptable sentences in particular languages to the meanings that they express. It is sometimes proposed that the simplest and most explanatory way of arranging the formal mechanisms of grammatical description is to allow them to produce unacceptable representations or derivations for some meanings and then to appeal to a global principle of economy to control this overgeneration. Thus there is an intuition common to many syntactic theories that a given meaning should be expressed in the most economical way, that smaller representations or shorter derivations should be chosen over larger ones. In this paper we explore the conceptual and formal issues of Economy as it has been discussed within the theory of Lexical Functional Grammar. In LFG the metric of Economy is typically formulated in terms of the size of one component of syntactic representation -- the surface constituent structure tree -- but it is often left unstated which trees for a given meaning are to be compared and how they are to be measured. We present a framework within which alternative explicit definitions of Economy can be formulated, and examine some phenomena for which Economy has been offered as an explanation. However, we observe that descriptive devices already available and independently motivated within the traditional LFG formalism can also account for these phenomena directly, without relying on cross-derivational comparisons to compensate for overgeneration. This leads us to question whether Economy is necessary or even useful as a separate principle of grammatical explanation.