In syntax, c-command (constituent command) is a relationship between the nodes of parse trees. It is analogous to siblings and all their dependents in family trees. C-command is closely associated with the phrase structure grammars of the Chomskyan tradition (Government and Binding, Minimalist Program), and it is not valid or applicable to the tree structures of other theories of syntax. For instance, c-command as it is commonly understood is hardly valid for the dependency-based parse trees of dependency grammars. C-command has served as the basis for many explorations and explanations of phenomena of syntax. It has been taken to be the basic configurational relation underlying binding and has played a central role in the analysis of diverse syntactic mechanisms, such as parasitic gaps and the scope of quantifiers.
Definition and example
The definition of c-command is based partly on the relationship of dominance: Node N1 dominates node N2 if N1 is above N2 in the tree (it is a parent, grandparent, etc.) and one can trace a path from N1 to N2 moving only downwards in the tree (never upwards). Based upon this definition of dominance, node A c-commands node B if and only if:
- A does not dominate B,
- B does not dominate A, and
- The first branching node that dominates A also dominates B.
For example, according to this definition, in the tree at the right,
- M does not c-command any node because it dominates all other nodes.
- A c-commands B, C, D, E, F, and G.
- B c-commands A.
- C c-commands D, F, and G.
- D c-commands C and E.
- E c-commands D, F, and G.
- F c-commands G.
- G c-commands F.
If node A c-commands node B, and B also c-commands A, it can be said that node A symmetrically c-commands its sister node B. If node A c-commands node B, but B does not c-command A, then A asymmetrically c-commands node B. The concept of c-command also deals with the relations between nodes of a phrase structure tree in terms of both phrasal and head government. Many variations of the c-command relationship have been proposed, m-command being prominent in this regard.
The term itself, i.e. c-command, was introduced by Tanya Reinhart in her 1976 dissertation and is a shortened form of constituent command. Reinhart herself thanks Nick Clements for suggesting both the term and its abbreviation. The concept Reinhart was developing was, however, not new to syntax. Similar configurational notions had been circulating for more than a decade. In 1963 Klima and Lees proposed a configurational relationship between nodes expressed as "in construction with" and Langacker proposed the notion of "command" in 1969.
Criticism and alternatives
The validity and importance of c-command for the theory of syntax is a debated issue. In most cases, c-command correlates positively with precedence (linear order), that is, when node A c-commands node B, it is usually the case that node A also precedes node B. Furthermore, basic S(V)O (subject-verb-object) word order in English correlates positively with a hierarchy of syntactic functions, subjects outranking objects. Subjects typically precede objects in declarative sentences in English and related languages. These two insights suggest that theories of syntax that build on c-command have misconstrued the importance of precedence and/or the hierarchy of syntactic functions. What c-command is intended to address is arguably more accurately analyzed in terms of precedence and the syntactic functions. Further, the c-command concept was developed primarily with its ability to address syntactic phenomena of English, a language with relatively strict word order. When confronted with the much freer word order of many other languages, the insights provided by c-command are less compelling, since linear order becomes less important.
As just suggested, the phenomena that c-command is intended to address may be more plausibly examined in terms of linear order and a hierachy of syntactic functions. Concerning the latter, some theories of syntax take a hierarchy of syntactic functions to be primitive. This is true of Head-Driven Phrase Structure Grammar (HPSG),. Lexical Functional Grammar (LFG), and dependency grammars (DGs). These frameworks posit a hierarchy of syntactic functions (SUBJECT > FIRST OBJECT > SECOND OBJECT > OBLIQUE OBJECT) as primitive, and they then explore and explain numerous mechanism of syntax based upon this hierarchy.
- Most syntax textbooks on generative grammar acknowledge, define, and build on the c-command concept. See for instance Radford (2004:75ff) and Carnie (2013:127ff.).
- The definition of c-command given here is taken from Haegeman (1994:147). The same or similar definitions of c-command can be found in numerous textbooks on syntax, e.g. Radford (2004:75) and Carnie (2013:127).
- The notion of asymmetric c-command plays a major role in Richard Kayne's (1994) antisymmetry theory.
- Carnie (2002:57) mentions this point, i.e. that Reinhart thanked Clements for suggesting the term c-command. The term c-command may also have been chosen so as to contrast with the similar notion kommand (often read as "k-command"), proposed by Lasnik (1976). See Keshet (2004) in this regard.
- The notion "in construction with" appeared in Klima and Lees' article in the journal Language (1963), and Langacker's notion of "command" appeared in an article in the journal Modern Studies of English (1969).
- See for instance Bruening's article in Language (2013). This article challenges the validity of c-command on more than one front.
- HPSG addresses the c-command effects in terms of o-command (obliqueness command). The syntactic functions are ranked in terms of their level of "obliqueness", subjects being the least oblique of all the functions. See Pollard and Sag (1994:248) and Levine and Hukari (2006:278f.).
- LFG addresses the c-command effects in terms of a straightforward ranking of syntactic functions associated with f-structure (functional structure). See Bresnan (2001:198).
- Concerning DGs emphasis on the importance of syntactic functions, see for instance Mel'c̆uk (1988:22, 69).
- Bresnan, J. 2001. Lexical Functional Syntax. Blackwell.
- Bruening, B. 2013. Precede-and-command revisited. Language 89(4), to appear.
- Carnie, A. 2002. Syntax: A generative introduction, 1st edition. Oxford: Blackwell Publishing.
- Carnie, A. 2013. Syntax: A generative introduction, 3rd edition. Malden, MA: Blackwell Publishing.
- Haegeman, 1994. Introduction to Government and Binding Theory, 2nd edition. Oxford: Blackwell Publishing.
- Kayne, R. 1994. The antisymmetry of syntax. Linguistic Inquiry Monograph Twenty-Five. MIT Press.
- Keshet, E. (2004-05-20). "24.952 Syntax Squib". MIT.
- Klima, E. and R. Lees. 1963. Rules for English pronominalization. Language 13, 17-28.
- Lasnik, Howard. 1976. Remarks on coreference. Linguistic Analysis 2, 1-22.
- Levine, R. and T. Hukari 2006. The unity of unbounded dependency constructions. Stanford, CA: CSLI Publications.
- Pollard, C. and I. Sag. 1994. Head-driven phrase structure grammar. Chicago: University of Chicago Press.
- Radford, A. 2004. English syntax: An introduction. Cambridge, UK: Cambridge University Press.
- Reinhart, T. 1976. The syntactic domain of anaphora. Doctoral dissertation, Massachusetts Institute of Technology. (Available online at http://dspace.mit.edu/handle/1721.1/16400).
- Reinhart, T. 1983. Anaphora and semantic interpretation. London: Croom Helm.
- c-command and pronouns
- Node relations, University of Pennsylvania
- Some Basic Concepts in Government and Binding Theory