Null Subjects in Child Wh-Questions* Hilary Sara Bromberg, Harvard University Kenneth Wexler, Massachusetts Institute oJ Technology I. Introduction Is there a deep structural relationship between the Optional Infinitive (OI) and Null Subject (NS) stages? We will provide evidence to support tile suggestion of Wexler (1992, 1994 footnote 44) that nonfinite verbs in the Oi stage of early child Englisll grammatically license a null subject, a suggestion further developed in a theory of the O! stage presented in Wexler 1995. The evi- dence we shall display emerges from tile particular pattern of null subjects that exists in declarative senlences and wh-quesiions. Hyams (1986) proposed thai the omission of subjects in child English represented the misseliing of the null-subject parameter. In Italian and other null-subject (pro-drop) languages, subjects may generally be omiued, subject to certain pragmatic constraints. In English and other non-null-subject languages, subjects may generally not be omitted. Work in generative grammar (e.g., Rizzi 1982) has assumed that a property of the INFL system licenses null subjects in null-subject languages, whereas the corresponding property of the INFL system in English does not license such subjects. For example, one ,night claim thai agreement, perhaps represented by an AGR node, licenses null subjects in Italian but not in English. The possibility thai there is a misseuing of the null-subject parameter has led Io much speculation about why such misseliing should occur, speculation •_ which has not received a satisfactory answer. Moreover, it would be quite an important property of the learning of parametric systems if in fact such misset- ling occurred. One purpose of this paper is to argue that there is no n|issetting of the null-subject parameter in early English and other non-null-subject lan- guages. Rather, null subjects are largely a result of Ihe O! stage. I If this conclu- sion turns out to be true, and there is actually no misseuing of the null-subject * We thank the Research Training Group in Language Acquisition and Computation (funded by NSF grant #DIR9113607) for providing an excellent research atmosphere. Thanks also to Carson Schiitze, Kevin Broihier, and Jenny Ganger for helpful comments and suggestions. This research wasconducted while HSB was a student at MIT. I The suggestion Ihal null subjects are relaled to the OI stage rather than to a misset par- ,meter was lirst made in Wexler 1992, 1994. Since then there have been a number of pa- pers which agree with this conclusion, in various ways, including Rizzi 1994b, Roeper and Rohrbacher 1995,and Sano and llyams 1994. MIT W_,rking Papers in Ltngui._tU_ 26, 221-247 Paperx on Language Pno_ essing and Acqut._ition. _ 1995 ttdary Sara Bromberg & Kenneth We,_ler tlilary Sara Bromberg and Kenneth Wexler Wh Null Subjecls subject in English, and the sentence is ungrammatical. (The standard assumption parameter, then the null-subject parameter will pattern with other basic inflec- is Ihat in "null-subject" hmguages finite TENSE licenses a particular kind of tional/clausal parameters--that is, it will be set correctly from at least the very empty subject: pro; English is not a null-subject language, so pro is not licensed asbeginningproposedofbytheWeproductixler (1995),on of unmuhi-wordder the assumptiutteranceson of(i.e.,Veraroundy Earl), 18Paramonths),meter. by finite TENSE in English.) Whatever the exact grammatical explanation, it is Setting. generally assumed that nonfinite TENSE licenses a null subject: PRO. "[bus, we might look to the existence of root infinitives to explain the presence of null sub- jects in early child language, specifically during the Ol stage, when such nonli- A nmjor discovery concerning early child language is that children in nile TENSE is rampant. many languages go through un Optional Infinitive (OI) stage (Wexler 1992, 1994). In this stage, the child produces nonfinite root verbs along with finite Wexler (1992, 1994) argues that the characterization of tbe Optional ones. Crucially, the finite and nonfinite verbs occur in different distributional Infinitive stage should be extended to English, despite the fact that morphologi- contexts; it has been shown that finite verbs and only finite verbs move in child cally one cannot distinguish the infinitive from the verb st_ma'itn English. Thus, sentences to. positions to which finite verbs move in the adult language. Thus, he claims that when children produce forms like (2) they are showing the key Wexler concluded that children in the Oi stage actually "know" the difference characteristic of the O! stage--they are omitting TENSE. between finite and nonfinite morphology, despite the fact that they are willing to omit TENSE in some sentences demanding it. (2) a she go h is an open question exactly in which sense TENSE is ouritted from b. she not go nonfinite root sentences. Certainly the surface tense marking is omitted The c. she going question is, though, exactly what is missing from the representation, the struc- tural description, of the nonfmite root sentence. As Wexler (1992, 1994) argued, In (2a), the (3rd singular) present TENS'E morpheme -s has been omitted. In some representation of TENSE other than the surface phonology had to be omit- (2b), TENSE has been omitted so that do-insertion, which is allowed onlg when ted; this is clear because the nonlinite root verb appears in the position of nonji- there is an unbound TENSE morpheme, does not occur. In (2c), TENSE has nite verbs. Thus, it is not a simple phonological "error." But exactly what is been omitted so that be is not required. (The assumpiion is that be is semanti- cally empty and only inserted to bind TENSE.) In addition, Harris and Wexler missing? is it the TENSE node? The projection headed by TENSE? Or simply a TENSI- li:ature? (in press) provide much empirical justification for the assumption that early En- glish represents the O1 stage; we will not review that evidence here (for further evidence, see Rice, Wexler, and Cleave in press). Wexler (1995) (see also lturris and Wexler in press) suggests that in the nonfinite sentences the entire TENSE projection, including the head TENSE, is Note that we are not attempting here to argue for any particular gram- missing in the nonfinite root (O!) sentences. One advantage to such an assump- matical characterization of the empty subject of non finite verbs. One possibility lion is that it explains why the infinitival morpheme to, which is often taken to is a characterization in terms of null-case (Chomsky & Lasnik 1991). Alterna- exist in the head of nonfinite TENSE, is missing in the OI sentences. Probably the results that we attain here can be carried out with a number of different as- lively, Wexler (1995) proposes that the TENSE projection is omitted from the Oi structures (for reasons that we will not delve into here) and that the lack of sumptions about what aspect of TENSE is missing in OI sentences. For example, TENSE means that in fact no case has to be assigned to the subject position. On •,, it is possible that in OI sentences, tt|e TENSE projection exists, but that the his analysis, the empty subject does not in fact need case of any kind--the case imsl/mmpast features which make the projection finite are missing In this paper filter is not part of the Minimalist framework That is, there is no UG principle we will not go into the question of whether Ibis assumption, or the assumption of that requires that all DPs have structural case, so long as there are no unchecked Wexler (1995) that the entire TENSE projection is missing, is best. features. Wexler (1992, 1994) suggested that null subjects in child English (and Let us try to specify these considerations a little more precisely, men- in child versions of other non-null-subject languages) might be related to the OI tioning alternative ways ot working them out. First, we can divide the different stage, rather titan to a misset parameter. In particular, it seems natural to suggest possible TENSE features in a sentence into 3 kinds: TENSEl+finitel, that root nonfinite verbs license null subjects, since in general nonfinite verbs It- TENSEl-finitel and -TENSE. The third, -TENSE, corresponds to the sintple tense empty subjects. For example, consider control constructions such as ( I ): lack of a TENSE projection at all, what we are assuming for the O! sentences. The first (TENSE[+finitel) is the standard, Nominative-assigning finite TI-NSE. (I) a Mary expects le to leavel The second (TENSEl-finiteJ) is the TENSE found in the standard "intinitival" b. *Mary expects [e leaves] constructions in adults, for ex.'unple in control sentence, it comes in English with a to morpheme, which we assume, again following standard assumptions, fills The empty subject e of(la) (traditionally called PRO) is licensed by the nonfi- the head of TENSE. nile TI-NSE of to le_zve. But the finite TENSE in (Ib) dt)es not license :m empty 223 222 Iiilary Sara Bromberg and Kenneth Wexler W/t Null Subjects easy to lind null subjecls ol finite verbs. There have been a number of ploposals Following Minimalist assumptions, TENSF.[-finile] assigns null ease. Io the effect thai child null subjects may be sortie khtd of "Topic-Drop" (de Ilaan This is Ihe case that is borne by only one kind of noun phrase, an entpty one. and "l'uijnman 1988; llyants & Wexler 1993; Wexler 1992, 1994) or "l)iary- Titus, Ihe slandard assumption is that the only kind of NP thai can be drawn Drop" (H:tegeman 199(); Rizzi 1994a), and we will assume that these proposals from Ihe lexicon with null case is the empty NP.