ATTRIBUTION OF MUTUAL UNDERSTANDING 383
determine the appeal in this case, it would be beneficial in
related circumstances to be able to quantify certainty of
interlocutor involvement in the dialogue. Interlocutor
involvement is the degree to which dialogue participants are
engaged in the conversation; this is more than the frequency and
balance of turn-taking, since a virtual monologue with
interleaved vocalizations such as “uh-huh” can demonstrate
ample turn-taking with little engagement. Notably, in this
example, the defendant provided answers to yes-no questions
that were coherent as a set. This appears to evidence a greater
level of engagement than if those turns were uniformly “yes.”
On the other hand, the defendant says little in each question-and-
answer to suggest that there was genuine understanding of what
the binary responses entailed, except the hedge, “I understand a
little bit.” There is no restatement in the defendant’s own words
of what was understood. It is precisely a method of quantifying
likelihood of understanding that is described and argued
appropriate for such forensic contexts in this article. Part III
returns to this transcript.
In assessing mutual understanding in conversation, it is
important to be clear about what constitutes a null hypothesis
and where the burden of proof lies in establishing an alternative
hypothesis. Its relevance is illustrated by the fact that the
question of whether the evolutionary niche of language is as a
cognitive tool for thought or as a cognitive tool for
communication remains a topic of debate. This is part of a
debate about whether language is a socially evolved construct or
a biologically evolved one. It is natural to compare human
language and human vision in this context. The eye is a delicate
and highly functional product of biological evolution. In
contrast, flaws of the linguistic system, including ambiguity at
every level of linguistic description, leave language as a poor
medium for communication. If one were to design a visual
system from scratch, the eye as it is now would likely be a part.
If one were trying to evolve a system as well-suited to
communication as the eye is for vision, one would strive for
telepathy rather than human language.^11
(^11) Cf. Steven Pinker & Paul Bloom, Natural Language and Natural