6.2.1 Inserting auxiliaries into I
In the previous chapter, we introduced the idea that dummy auxiliaries are inserted into a structure when the verb is unable to support a bound morpheme. Consider what happens with regard to a bound inflectional element such as the present tense morpheme s:
| (19) | a | |
| ‘he has arrived’ | ||
| b | ||
| ‘she is living in London’ |
In both of these examples, the verb moves from the V position to support the aspectual morphemes. As a consequence of English stems being unable to support more than one overt morpheme, the verb cannot move further. As the inflection is a bound morpheme it needs supporting and in this case the auxiliaries are inserted directly into the inflectional slot. Note that which auxiliary is used depends on the aspectual element heading the vP complement of the inflectional element. A perfective aspectual morpheme determines the supporting auxiliary to be have while the progressive morpheme determines the supporting auxiliary to be be. With a slightly more complex example, we see that this is a very general process:
| (20) | ||
| ‘they have been staying with my parents’ |
In this case there are two aspectual morphemes as well as the inflection to be supported. The verb moves to the lowest one and cannot move further. Therefore two auxiliaries are inserted: be, determined by the progressive, is inserted onto the perfective morpheme which takes the phrase headed by ing as its complement, and have, determined by the perfective, is inserted onto the tense morpheme (in this case null) which takes the phrase headed by the perfective morpheme as its complement.