Of these feature types, to my knowledge only the modality and descriptive features have been investigated in
neural terms.Within the context of our psychological concerns, it seems to me that this overall organization of feature types is not
something that can be ascribed to learning. This is a bare skeleton of the framework in terms of which learning can
take place. On the other hand, since this organization plays a role in perception, imagery, and action as well as
language, we do not have to ascribe it to narrow Universal Grammar: it is a central part of all cognition.
10.7 Application to theory of reference
Section 10.5 showed how the act of creating or understanding an expression with deictic reference can be reduced
functionally to the association or binding of a linguistic entity with a percept. We are now in a position to sharpen and
generalize this account.
The indexical feature of a percept is the crucial feature for linguisticreference.If there is no indexical feature to which
descriptive features can be bound, there is nothing to which a deictic or other referring linguistic expression can be
attached either: there is no‘that’there.
We have already seen how this account extends to some of the problematic entities mentioned in section 10.3.
Consider again virtual objects such as the square subtended by four dots. Although there is nothing“actually out
there,”the visual syste mconstructs a percept with all the right features for“something out there.”Hence there is
something“out there”in theperceivedworld, and we can refer to it. Next consider the unicorn in my dream. There is a
remembered entity which has an indexical feature and descriptive features in the visual modality (in particular a one-
horned shape). Inmemory, itis assigned thevaluationinternal, so itis notexperiencedany more as having been“in the
world.”Still, because it has an indexical feature, it can be connected to a referential expression.
Returning to the standard literature on reference: Frege (1892) made the distinction between the sense and the
referenceofan expression byciting thewell-known exampleThe morning star is the evening star. Inhis analysis, twosenses
are attached to the same reference. We can understand Frege's example in present terms as reporting the merger of
indexicals associated with different descriptive features, exactly as in our example of the circle that is sometimes red
and sometimes blue. So Frege's problem is not a uniquelylinguisticproblem; rather, it lies in a more general theory of
how the f-mind keeps track of individuated entities.