Antisymmetry

In linguistics, antisymmetry is a theory of syntactic linearization presented in Richard Kayne's 1994 monograph The Antisymmetry of Syntax. The crux of this theory is that hierarchical structure in natural language maps universally onto a particular surface linearization, namely specifier-head-complement branching order. The theory derives a version of X-bar theory. Kayne hypothesizes that all phrases whose surface order is not specifier-head-complement have undergone movements that disrupt this underlying order. Subsequently, there have also been attempts at deriving specifier-complement-head as the basic word order.

Antisymmetry as a principle of word order is reliant on assumptions that many theories of syntax dispute, e.g. constituency structure (as opposed to dependency structure), X-bar notions such as specifier and complement, and the existence of ordering altering mechanisms such as movement and/or copying.

The theory is based on a notion of asymmetric c-command, c-command being a relation between nodes in a tree originally defined by Tanya Reinhart (1976). Kayne uses a simple definition of c-command based on the "first node up". However, the definition is complicated by his use of a "segment/category distinction". A category is a kind of extended node; if two directly connected nodes in a tree have the same label, these two nodes are both segments of a single category. C-command is defined in terms of categories using the notion of "exclusion". A category excludes all categories not dominated by both its segments. A c-commands B if every category that dominates A also dominates B, and A excludes B. The following tree illustrates these concepts:

AP₁ and AP₂ are both segments of a single category. AP does not c-command BP because it does not exclude BP. CP does not c-command BP because both segments of AP do not dominate BP (so it is not the case that every category that dominates CP dominates BP). BP c-commands CP and A. A c-commands C. The definitions above may perhaps be thought to allow BP to c-command AP, but a c-command relation is not usually assumed to hold between two such categories, and for the purposes of antisymmetry, the question of whether BP c-commands AP is in fact moot.

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