Grammatical Functions

We distinguish four types of grammatical functions:

1. The predicate
   
2. The subject
   
3. The complements
   
   1. The direct object
      
   2. The indirect object
      
   3. The predicative complement
      
   4. The oblique complement
      
4. Modifiers (Adjuncts)
   

The differences can be accounted for using several criteria

Position in the structure

• The predicate of a clause is the highest VP (or AuxP).
• The subject is external to the predicate.
• Complements and modifiers are both internal to the predicate.
• The complements are sisters to V.
• The modifiers are sisters to VP.
• Modifiers usually do not stand between the V and its complements

Pronominalization

• A pro-VP form such as do so cannot combine with a complement, but it can combine with a modifier.
• Pat put a book [on the shelf], and Mary did so into the drawer. (on the shelf is a complement)
• Pat read a book [in the library], and Mary did so at home. (in the library is a modifier)

Obligatoriness

• Complements are syntactically obligatory. Their form and number is determined by the verb.
  • Note: complements can also be optional (Pat ate (shrimp).)
• Modifiers are syntactically optional. Their form and number is independent of the VP they combine with.

Uniqueness

• Every complement function can occur at most once with a given predicate. Modifiers can occur in arbitrary numbers.

Semantic autonomy

• The interpretation of complements is determined by the verb, the interpretation of modifiers is independent of the verb:
  • Pat relies [on Kim]. (complement, on does not contribute any meaning)
  • Pat lies [on the bed]. (locative modifier, on expresses a relative position)
• The existence or involvement of a complement is semantically implied by the specific verb. E.g. eat implies that some object is involved in the activity.
• The compatibility of a VP with a certain modifier is a property not of the particular verb, but of a larger verb class.

  ← Phrases          → Predicate