A Typology of Word Categories3.2 Predicates and arguments
To understand the difference between thematic and functional categories we first need
to introduce concepts to do with how the elements of a sentence can be related to each
other. Take a simple sentence:
(33) Peter chased Mary
This sentence describes an event which can be described as ‘chasing’ involving two
individuals, Peter and Mary, related in a particular way. Specifically, Peter is the one
doing the chasing and Mary is the one getting chased. The verb describes the character
of the event and the two nouns refer to the participants in it. A word which functions
as the verb does here, we call a predicate and words which function as the nouns do
are called arguments. Here are some other predicates and arguments:
(34) a Selena slept
argument predicate
b Tom is tall
argument predicate
c Percy placed the penguin on the podium
argument predicate argument argument
In (34a) we have a ‘sleeping’ event referred to involving one person, Selena, who was
doing the sleeping. In (34b) the predicate describes a state of affairs, that of ‘being tall’
and again there is one argument involved, Tom, of whom the state is said to hold.
Finally, in (34c) there is a ‘placing’ event described, involving three things: someone
doing the placing, Percy, something that gets placed, the penguin, and a place where it
gets placed, on the podium.
What arguments are involved in any situation is determined by the meaning of the
predicate. Sleeping can only involve one argument, whereas placing naturally involves
three. We can distinguish predicates in terms of how many arguments they involve:
sleep is a one-place predicate, see is a two-place predicate involving two arguments
and place is a three-place predicate.
Moreover, the nature of the arguments is also largely determined by the meaning of
the predicate. Compare the following:
(35) a Harold hit Henry
b Sam saw Simon
In the first case, Harold is the one doing the hitting and Henry is the one getting hit
whereas in the second Sam does the seeing and Simon gets seen. However, these
arguments play very different roles in the two events. With hit the one doing the
hitting consciously performs an action and the one who gets hit is affected in some
way by this. We call an argument who deliberately performs an action an agent and
one who or which is acted upon a patient. With see, the arguments are not interpreted
as agent and patient however: Sam is not performing any action and Simon is not
getting acted upon in (35b). Instead, we call these arguments experiencer, for the one
who does the seeing, and theme, for the one who gets seen. Collectively, we call terms
such as agent and patient, thematic roles, or -roles for short. I will not provide a
definitive list of possible theta roles and their definitions here as such a list does not