From Paul J. Hopper and Elizabeth Closs Traugott
Grammaticalization, Chapter 4
CUP, 2nd revised ed. (in press)
Recently the fundamental importance of conceptual metonymy in language in general has been widely recognized. Indeed, there has been a major shift in thinking and it is coming to be increasingly recognized as "probably even more basic [than metaphor] to cognition" (Barcelona 2000: 4). As a cognitive process in which "one conceptual entity ... provides access to another conceptual entity ... within the same domain' (Kövecses and Radden 1998: 38), metonymy points to ("indexes") relations in contexts that include interdependent (morpho)syntactic constituents. In an utterance such as (19) the verb go invites the conversational inference that the subject arrived at a later time at the destination, and the purposive to, introducing a subordinate clause, invites the conversational inference that someone intended the marriage to occur:
(19) I was/am going to be married. (in the sense 'I was/am going for the purpose of getting married')However, this implicature can be canceled:
(20) I was going/on my way to be married, but on the plane I changed my mind and decided to join the Army.
We hypothesize that the future meaning of be going to was derived by the semanticization of the dual inferences of later time indexed by go and purposive to, not from go alone. Indeed, we hypothesize that the inference from purposive to must have played a significant role in the grammaticalization of be going to given that the major syntactic change involved in the development of the auxiliary is the rebracketing of [[...be going] [to S]] as [...be going to V X] (Chapter 1.1). The progressive be-ing indexed activity in process, and so motivated the tendency for be going to to be interpreted as a purposive that was relevant to the reference time of the clause and likely to be imminent (see Bybee and Pagliuca 1987, Pérez 1990, who differ from the analysis presented here mainly in treating the change as a case of metaphorization). To appreciate the importance of the relationship between to and go, in the development of auxiliary be going to, consider the following possible early instance:
(21) Thys onhappy sowle...was goyng to be broughte into helle for the synne and onleful [unlawful] lustys of her body. (1482, Monk of Evesham [OED go 47b])
This can be understood as an expression of motion in the context of the belief that after death the soul goes on a journey with the purpose of being rewarded or punished for actions in life. Note that in this example the passive demotes the inference that the subject of go is volitional or responsible with respect to the purposive clause. Because the destination of the journey (hell) is an adjunct not of goyng to but of broughte, the directionality of going is also demoted, and the inference of imminent future resulting from the purposes of the judges of the dead is promoted.
Similarly, in the passage in (22) the answer to whither away is (to) a messenger, and I am going to deliver them seems best understood as answering the question (why) so fast?, in other words, it seems more informative if it is inferred to answer the question in terms of purposes rather than directions:
(22) Duke Sir Valentine, whither away so fast? Val. Please it your grace, there is a messenger That stays to bear my letters to my friends, And I am going to deliver them. (c. 1595, Shakespeare, Two Gentlemen of Verona III.i.51)
The full semanticization (and grammaticalization) of be going to is evidenced when the following subject and/or the verb is incompatible with purposiveness, for example, an inanimate subject or a verb of mental experience such as hear, or like. Once the semanticization of later time/future had occurred, the will future could no longer be used with be going to, presumably because it had become partially redundant, and did not fit the auxiliary verb structure into which the construction had been absorbed. (Note, however, that the will-future can still occur in the main verb construction be going to, as in I will be going to visit Aunt Mildred tomorrow.)
References
Barcelona, Antonio, ed. 2000. Metaphor and Metonymy at the Crossroads: A Cognitive Perspective. Berlin: Mouton de Gruyter.
Bybee, Joan L., and William Pagliuca. 1985. Cross-linguistic comparison and the development of grammatical meaning. In Jacek Fisiak, ed., Historical Semantics, Historical Word-formation. 59-83. Berlin: Mouton de Gruyter.
Kövecses, Zoltán and Günter Radden. 1998. Metonymy: developing a cognitive linguistic view. Cognitive Linguistics 9: 37-77.
Pérez, Aveline. 1990. Time in motion: grammaticalisation of the be going to construction in English. La Trobe University Working Papers in Linguistics 3: 49-64.