Gram - SEAS

208 7 Grammaticalizatioll across clauses
will be one factor that determines whether or not they come to be regarded by the
speech community as "grammatical" (Bybee and Hopper 2002). (Other factors
are, of course, more obviously social: acceptance by broadcast and print media,
endorsement by educational and other institutions, and so on.)
Our example is that of the emergence in PDE of "evidential parentheticals."
Thompson and Mulac (1991) suggest that verbs of propositional attitude such as
think and guess with first- and second-person subjects are coming to be parentheticals.
Such verbs typically serve to introduce propositions, as in (72), where think
is the main verb and the sentence serves as an assertion that a certain belief is held
by the speaker or a question concerning the belief state of the hearer:
(72) a. I think that the coup was planned by the CIA.
b. Do you think that the coup was planned by the CIA?
On the other hand, they may serve to qualify an assertion; they are then known as
parentheticals:
(73) a. I think Commander Dalgleish writes poetry.
b. Commander Dalgleish writes poetry, I think.
Here the main verb is writes, and the sentence is a (qualified) assertion about
an activity of Commander Dalgleish, not about the state of mind of the speaker.
Alternatively, think and guess with second-person subjects may serve to indicate
interactive communication:
(74) What's the point of that, do you think? (fhompson and Mulac 1991: 322)
In such circumstances, there is no complementizer that and the parenthetical receives
less stress than the ma.in verb. Moreover, parenthetical //you think, //you
guess have the same syntax as an adverb, in that they are not restricted to one
position in the clause. A change of meaning is also noticeable. When it is par­
enthetical, / think is less certain than when it is non-parenthetical; the speaker
is not staking out an epistemological position, but indicating the degree of vali­
dation of the statement by suggesting that he or she has no direct evidence for
it. In other words, Thompson and Mulac suggest, the parenthetical is begin­
ning to serve the kind of function often served by specialized c1itics and parti­
cles expressing such modal distinctions as "witnessed," "deduced," "speculative,"
"hearsay," functions largely expressed in PDE by epistemic modals (e.g., They
must be students 'I conclude they are students') and by adverbs such as evidently,
apparently, etc.
From the perspective of the continuum of clause integration, we can see such
parentheticals as instances of a complex sentence consisting of the nucleus with a
verb of propositional attitude and a margin (e.g., that Commander Dalgleish writes