An ergative verb is one which can be used both transitively (with an object) and intransitively (without an object), and whose object when the transitive construction is used is the same as the subject of the intransitive construction. For example:
Ann closed the door. (Subject Verb Object - transitive)
The door closed. (Subject Verb - intransitive)
I boiled some water for tea. (Subject Verb Object - transitive)
The water boiled. (Subject Verb - intransitive)
David stopped the car. (Subject Verb Object - transitive)
The car stopped. (Subject Verb - intransitive)
In all of these examples, the object of the transitive construction becomes the subject in the intransitive construction.
This means that it is only in the transitive construction that the subject is also the agent - ie the person/thing etc that performs the action. The intransitive construction thus allows us to avoid mentioning the agent. There a number of cases where this may be useful - for example:
- If the agent is irrelevant, obvious or expected - eg The lesson ended / The snow melted / The plane landed - rather than The teacher ended the lesson / The sun melted the snow / The pilot landed the plane.
- To create suspense - for example, in a thriller when the writer doesn't want the reader to find out exactly who or what causes the action - eg Suddenly the door opened and ...
- The speaker/writer wants to focus on a result rather than its cause, possibly because there are too many contributing causes to name - eg The level of inflation increased during May.
Common ergative verbs include :
a) Verbs describing the start and finish of something : eg begin end finish start stop -
b) Verbs connected with heating and cooling : eg bake boil cook defrost freeze fry
melt roast - I defrosted the fridge this morning / The fridge defrosted this morning
when the power went off.
c) Verbs connected to movement : eg back close crash drive fly open reverse run sail shut - John was driving the car at 90 mph / The car was driving at 90 mph
d) Verbs expressing some other type of improvement or damage : eg break crack improve tear worsen - The government has worsened the situation / The situation has worsened