Tag Question Transformation

The standard or classical, model of transformational generative grammar posits two levels of representation for sentences, an abstract deep structure of meaning relationships and a concrete surface structure of realised sentences. The surface structure is derived from the deep structure by a set of rules, or transformations. It is the transformational part that proves useful in the correcting of sentence mechanics. What makes the transformational part particularly useful is that transformational rules are sensitive to various syntactic categories.

Tag Questions are used to express the speaker attitudes, expectations and suppositions concerning the content of his utterance, the speech situation and the hearer. Tag Question consists of a predicate, a subject (in inversion) and an optional negative particle. The choice of the predicate depends on the preceding verb: a full verb is taken up by a corresponding form of the periphrastic verb do (“He likes her, doesn’t he?”), a helping verb, no matter if it has been deleted or not, is repeated in the tag question (“He couldn’t see me, could he?”, “Going, are you?”). The subject consists of a personal pronoun that refers anaphorically to the preceding subject.

Take, for example, the rule of Tag-Formation, which relates the a and the b sentences in each pair of sentences below:

1. 1. a. John can swim.
      b. John can swim, can’t he?
   2. a. The neighbours will be moving to Los Angeles.
      b. The neighbours will be moving to Los Angeles, won’t they?
   3. a. The car with the mag wheels and the tinted windows has been washed.
      b. The car with the mag wheels and the tinted windows has been washed, hasn’t it?
   4. a. Betty studied her chemistry last night.
      b. Betty studied her chemistry last night, didn’t she?

While linguists have formulated Tag-Formation in different ways, most agree that the rule essentially copies certain constituents of a sentence to create the tag at the end. Tags, like Yes or No interrogatives, involve the inversion of the auxiliary:

John has gone, hasn’t he?

The grammatical elements which get copied are the first auxiliary verb (if none occurs, a form of do is added instead), the verb tense, the negative not in contracted form (if the sentence is positive), and the subject noun phrase in pronominal form.

Although Tag-Formation is a complex rule involving several operations, all native speakers of English have implicit knowledge of the rule; otherwise, they would be unable in daily life to transform the sentences in 1-4 into their corresponding tag questions.

A second and more important point follows: if native speakers of English already know the rule of Tag-Formation, they must also know the syntactic categories involved in the rule; that is, native speakers of English, whatever their formal background in grammar, already have an underlying knowledge of such syntactic categories as sentence, auxiliary verb, tense, negative, and (subject) noun phrase. To understand the notion of a sentence fragment, students need to make use of the concept of the sentence (i.e., a sentence fragment is only a “part” of a sentence). Tag-Formation operates on only declarative (and imperative) sentences, not fragments. If this is so, the rule will operate on sentences such as 1a, 2a, 3a, and 4a but not on sequences such as:

5. Although John will stay home.

6. Whatever was bothering the neighbours.

7. Who saw that she had been trying.

8. Waiting for the show to begin.

But from the fragment “A nice day,” we can derive “A nice day, isn’t it?” However, we can utilise such examples to reinforce the idea that all tag-questions derive from underlying declarative sentences and not parts of them. By undoing the effects of Tag-Formation and other transformational rules (E.g., deleting the -n’t and putting the copied elements of the tag back into their original positions), We can demonstrate that “A nice day, isn’t it?” actually derives from “It is a nice day” (the underlying declarative sentence) and not from “A nice day” (a part of the underlying declarative sentence). The derivation of “A nice day, isn’t it?” proceeds thus: “It is a nice day” (underlying declarative sentence) to “It is a nice day, isn’t it?” (derived sentence after the Tag-Formation rule has applied) to “A nice day, isn’t it?” (derived sentence after another rule has deleted it and is in the main clause). This derivation, incidentally, reveals an exception to the simplified description of the Tag-Formation rule.

Sample Tag Question Derivation:
John has gone.

You aren’t coming.

You remember the lesson from last week.