MANDARIN CLAUSE LINKAGE 227truth value), neither (52b) nor (52c) asserts that reading took place. What
is asserted is that if reading were to take place, understanding would result
(in the case of (52b)) or would not result ((52c)). The particles bu and de
operate not on either of the predicates, but on the CAUSE in the logical
structure of the serialization. Although sentences (52b) and (52c) could be
considered to be "irrealis" in comparison to (52a), this construction is not
an irrealis marker, rather the irrealis interpretation is a logical by-product
of the fact that it is the status of the causality relation between the two pred
icates that is being asserted, not the status of the predicates as indicating
real events or not.
The Potential Complement construction is often considered to be a
modality marker, because it can often be paraphrased with modals like
néng "can" or huí "can", "know how to". This presents a problem, because
if this were indeed a case of marking modality, the Potential Complement
construction could not be a case of nuclear juncture, modality being a core
operator. Yet in all other ways, such as scope of operators and shared argu
ments between predicates, it looks like a nuclear juncture. Perhaps the sol
ution lies in the subtle distinctions that sometimes exist between usage of
true modals and Potential Complements: where the distinction exists, it is
that true modals express whether the action or event in question is allowed/
prevented because of moral imperative, while the Potential Complement
expresses whether it is allowed/prevented by circumstances. For example:
(53) a. Wo bù néng mài.
I NEG can buy
"I can't buy (it)." (Because Mom won't let me, because I'm
underage, because it's immoral etc.)
b. Wo mai bu dàolbu qï.
I buy NEG arrive/NEG arise
"I can't buy (it)." (Because it's not available/ too expensive.)
In (53a), buying should not be done because of possible consequences,
while in (53b) buying, even if attempted, cannot be accomplished. The
modal interpretation here is a logical by-product of the causality chain
being negated. The modal meaning is asserted in (53a), but only inferred in
(53b).^5
This may also explain why the Potential Complement occurs much
more often in the negative, or, if it does occur in the affirmative, it is as the
answer to a question or an assertion contrary to expectation. Since the pos-