Functional Categories: DP, IP, and CP

Functional heads have specific properties which distinguish them from lexical categories.

(a) Functional heads carry grammatical properties rather than lexical/semantic properties:

INFL (or I) bears finiteness and agreement features;
DET (or D) bears features such as number, gender, definiteness, case (possessive);
COMP (or C) bears clause-type features such as declarative or interrogative.

(b) Functional heads take one specific complement:

COMP takes an IP-complement;
INFL takes a VP-complement;
D takes an NP-complement.

D as a functional head
INFL as a functional head
COMP as a functional head

Exercises on functional categories