In linguistics, the empty category principle (ECP) was proposed in Noam Chomsky's syntactic framework of government and binding theory. The ECP is supposed to be a universal syntactic constraint that requires traces to be properly governed.
Proper government is defined as follows:
- A properly governs B iff A theta-governs B or A antecedent-governs B.
- A theta-governs B iff A governs B and A theta-marks B.
- A antecedent-governs B iff A governs B and is coindexed with B.
The ECP is a way of accounting for, among other things, the empirical fact that it is generally more difficult to move up a wh-word from a subject position than from an object position.
The intermediate traces must be deleted because they cannot be properly governed; theta-government is impossible because of the position they occupy, Spec-CP; the only possible antecedent-governor might be an overt NP (a wh-word), but the Minimality Condition would always be violated because of the tensed I (which must be present in all matrix clauses), the tensed I would c-command the intermediate trace but it would not c-command the wh-word. So we have to say that intermediate traces must be deleted at LF so that they can avoid the ECP.
In the case of object extraction (the trace is a complement of VP), theta-government is the only possible option. In the case of subject extraction (the trace in Spec-IP), antecedent-government is the only possible option.
If the trace is in Spec-IP and we have an overt complementizer (such as that), the sentence is ungrammatical because the ECP is violated. The closest potential governor would be the complementizer, which cannot antecedent-govern the trace because it is not coindexed with it (and theta-government is impossible since trace is in Spec-IP).
For example, in the sentence Who do you think (that) John will invite? the ECP works in the following way (the structure is given for the embedded clause only):
Famous quotes containing the words empty, category and/or principle:
“Through the dark cold and the empty desolation,
The wave cry, the wind cry, the vast waters
Of the petrel and the porpoise. In my end is my beginning.”
—T.S. (Thomas Stearns)
“The truth is, no matter how trying they become, babies two and under don’t have the ability to make moral choices, so they can’t be “bad.” That category only exists in the adult mind.”
—Anne Cassidy (20th century)
“You may call a jay a bird. Well, so he is, in a measure—because he’s got feathers on him, and don’t belong to no church, perhaps; but otherwise he is just as much a human as you be. And I’ll tell you for why. A jay’s gifts and instincts, and feelings, and interests, cover the whole ground. A jay hasn’t got any more principle than a Congressman.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)