Shifting (syntax)

Further examples

The syntactic category of the constituents involved in shifting is not limited; they can even be of the same type, e.g.

It happened on Tuesday due to the weather.

It happened due to the weather on Tuesday.

Sam considers him a cheater.

Sam considers a cheater anyone who used Wikipedia.

In the first pair, the shifted constituents are PPs, and in the second pair, the shifted constituents are NPs. The second pair illustrates again that shifting is often motivated by the relative weight of the constituents involved; the NP anyone who used Wikipedia is heavier than the NP a cheater.

The examples so far have shifting occurring in verb phrases. Shifting is not restricted to verb phrases. It can also occur, for instance, in NPs:

the book on the shelf about linguistics

the book about linguistics on the second shelf down from top

the picture of him that I found

the picture that I found of that old friend of mine with funny hair

These examples again illustrate shifting that is motivated by the relative weight of the constituents involved. The heavier of the two constituents prefers to appear further to the right.

The example sentences above all have the shifted constituents appearing after their head (see below). Constituents that precede their head can also shift, e.g.

Probably Susan left.

Susan probably left.

Certainly that happened more than once.

That certainly happened more than once.

Since the finite verb is viewed as the head of the clause in each case, these data allow an analysis in terms of shifting. The subject and modal adverb have swapped positions. In other languages that have many head-final structures, shifting in the pre-head domain is a common occurrence.

Theoretical analyses

If one assumes relatively flat structures, the analysis of many canonical instances of shifting is straightforward. Shifting occurs among two or more sister constituents that appear on the same side of their head. The following trees illustrate the basic shifting constellation in a phrase structure grammar (= constituency grammar) first and in a dependency grammar second:

The two constituency-based trees show a flat VP that allows n-ary branching (as opposed to just binary branching). The two dependency-based trees show the same VP. Regardless of whether one chooses the constituency- or the dependency-based analysis, the important thing about these examples is the relative flatness of the structure. This flatness results in a situation where shifting does not necessitate a discontinuity (i.e. no long distance dependency), for there can be no crossing lines in the trees. The following trees further illustrate the point:

Again due to the flatness of structure, shifting does not result in a discontinuity. In this example, both orders are acceptable because there is little difference in the relative weight between the two constituents that switch positions.

An alternative analysis of shifting is necessary in a constituency grammar that posits strictly binary branching structures. The more layered binary branching structures would result in crossing lines in the tree, which means movement (or copying) is necessary to avoid these crossing lines. The following trees are (merely) representative of the type of analysis that one might assume given strictly binary branching structures:

The analysis shown with the trees assumes binary branching and leftward movement only. Given these restrictions, two instances of movement might be necessary to accommodate the surface order seen in tree b. The material in light gray represents copies that must be deleted in the phonological component.

This sort of analysis of shifting has been criticized by Ray Jackendoff, among others. Jackendoff and Culicover argue for an analysis like that shown with the flatter trees above, whereby heavy NP shift does not result from movement, but rather from a degree of optionality in the ordering of a verb's complements. The preferred order in English is for the direct object to follow the indirect object in a double-object construction, and for adjuncts to follow objects of all kinds; but if the direct object is "heavy", the opposite order may be preferred (since this leads to a more right-branching tree structure which is easier to process).

A mystery

From a generativist's perspective, a mysterious property of shifting is that in the case of ditransitive verbs, a shifted direct object prevents extraction of the indirect object via wh-movement:

Whom did you give the books written by the venerable Professor Plum to?

*Whom did you give to the books written by the venerable Professor Plum?

Some generativists use this example to argue against the hypothesis that shifting merely results from choice between alternative complement orders, a hypothesis that does not imply movement. Their analysis in terms of a strictly binary branching tree resulting from leftward movements would in turn be able to explain this restriction. However, there are at least two ways of countering this argument: 1) in case one wants to explain choice, if choice is assumed to be performed between possible orders, the impossible order is not in the linguistic potential and it cannot be chosen; however, 2) in case one wants to explain generation, that is, to explain how a linguistic potential comes to exist in a situation, one can explain this phenomenon in terms of generation and avoidance rules: for instance, one of the reasons for avoiding a wording in potentiality would be an ordering in which a preposition falls before a nominal group by accident as in the example above. In other words, from a functional perspective, we either recognise that these fake clauses are none of the clauses we can choose from (choice of possible clauses) or we say that they are generated and avoided because they might cause listeners to misunderstand what the speaker is saying (generation and avoidance).