flagging) of truth values to sentences is immediate; this is an example of the ex-
tralinguistic assignment problem discussed in §7.5. These two problems suggest
that the traditional view of radical interpretation needs radical revision.
7.5 The Extralinguistic Assignment Problem
In order for radical interpretation to work various principles, such as the princi-
ple of charity, have to be assumed. In Roberts (1998) [36] there is a version
of this called cooperation dominance. These principles contain the idea that
people communicate truthfully more often than not, and that details of their
behaviour give indications of the truthfulness of their communication: hence it
is possible to use extra-linguistic information to assign the truth values
to sentences. Instead of just the bivalent assignment of
B = {true, f alse}, (3)
extra-linguistic information could assign different structure such as those of
more complex logic, such as fuzzy logic, or alternatively a series of real numbers
representing the probability that the sentence is true, its complexity and so on,
see §8.2. However a problem arises because the existence of a name strategy
shows that, at the time an apparently true statement is uttered the quantity
of truth is not optimal; that the statement is apparently true is post hoc as it
assumes that the listener posses the information, consciously or unconsciously,
to transcribe it to the relevant true statement. A way that this could be ac-
commodated in the usual theory is be requiring that the transcription process
is contained in the passing theory of the language; but then it seems hard to
justify referring to the extralinguistic information assigned as being ”truth”. A
better description is to assume that the extralinguistic assignment is of relevant
information, c.f. Sperber and Wilson (1987) [43]; the traditional case is a sub-
case of this, as most relevant information is true, but also it is possible to state
irrelevant true statements. That truth is not the only quality needed for facility
of communication has been noted by Church (1956) [7] p.2-3
”For purposes of logic to employ a specially devised language, a for-
malized language as we shall call it, which shall reverse the tendency
of the natural languages and shall follow or reproduce the logical
form [here having the restricted meaning that statements can be
assigned bivalent truth values rather than be flagged by a formal
system] - at the expense, where necessary, of brevity and facility of
communication.”
It is possible to quantify information, see the P-model of Roberts (1998b) [37],
but quantifying relevant information presents problems: perhaps the vehemence
or Fregian force with which a sentence is stated could lead to such quantifica-
tion. Flagging by Fregian force is unrealistic as it implies that by shouting
louder makes a statement more true, a better flag is relevant information. Rele-
vant information is discussed in the commentary on Sperber and Wilson (1987)
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