good reason is that individual body parts are paradigmatically identified

Another
Somatic Proprioception and the Bodily Self 155
good reason is that individual body parts are paradigmatically identified
in terms of hinges. The forearm, for example, is the volume between the
elbow and the wrist. The palm of the hand is the volume bounded by the
wrist and the knuckles. The calf is the volume of leg that falls between
the knee and the ankle. Using hinges provides a nonarbitrary way of segmenting
the body that accords pretty closely with how we classify body
parts in everyday thought and speech.
Let me start by explaining how the hinges can be deployed to determine
any given A location. A particular bodily A location is specified relative
to the hinges that bound the body part within which it is located. A particular
point in the forearm is specified relative to the elbow and the wrist.
It is the point that lies on the surface of the skin at such and such a distance
and direction from the wrist and such and such a distance and direction
from the elbow.23 This mode of determining A locations secures the
defining feature of an A location, which is that a given point in a given
body part will have the same A location irrespective of how the body as
a whole moves or of how the relevant body part moves relative to other
body parts. The A location of a given point in a given body part will
remain constant in both those movements, because neither of those movements
brings about any changes in its distance and direction from the
relevant hinges. Note, however, that this holds true only if the fixed points
are restricted to those hinges that bound the relevant body part. If the number
of fixed points were expanded to include nonbounding hinges, this
would have the undesirable consequence that the A location would vary.
I turn now to the more complicated issue of B location. The first point
to observe is that it is individual A locations that have particular B locations.
This is clear from situations (1) and (2) described above, in which
a pain retains a constant A location in two different B locations. In each
situation what has the relevant B location is the pain that is A-located at
a particular point in the sole of my foot. It is not the pain simpliciter that
in (2) is B-located just above and to the left of my left knee and down and
slightly left of my left shoulder, but the pain in the sole of my foot. This
provides an important clue as to how the account of B location ought to
proceed. If what has a given B location is an A location and A locations
are identified within given body parts (relative to the hinges that bound
those body parts), then it seems we can map an A location onto a B loca-
156 Chapter 6
tion if we can plot the location of the given body part. How might this
be done?
Body parts have been defined as body segments bounded by hinges.
These hinges afford a range of movements in three dimensions (with some
hinges, like the shoulder, affording a greater range of movements than
others, like the elbow). A hinge such as the wrist allows the hand to be
positioned in one of a range of orientations relative to the lower arm. The
basic idea in mapping A locations onto B locations is to specify what
orientation the body part is in relative to the hinge. Take a point in the
center of the palm of the hand. That point has its A location relative to
the hinges that bound the palm of the hand, while its B location is given
by the orientation of the palm of the hand relative to the wrist. Of course,
this is not enough to fix a unique B location, for it fails to register the
changing B location of a point in the center of the palm of my hand as I
keep my hand in the same orientation relative to my wrist but raise it
above my head. Accommodating such changes in B locations is possible
only if the orientation of the relevant body part is relativized more widely.
In the example of the point in the palm of the hand, the orientation of
the wrist needs to be fixed relative to the elbow, and the orientation of
the elbow relative to the shoulder. That would provide a unique B location
within the arm and would also specify the location of the arm relative
to the torso.
The general model, then, for the identification of B locations is as follows.
A particular constant A location is determined relative to the hinges
that bound the body part in which it falls. That A location will either fall
within the (relatively) immoveable torso, or it will fall within a moveable
limb. If it falls within the (relatively) immoveable torso, then its B location
will also be fixed relative to the hinges that bound the torso (neck, shoulders,
and leg sockets). If, however, that A location falls within a moveable
limb, then its B location will be fixed recursively relative to the hinges
that lie between it and the immoveable torso. This enables any given B
location to be calibrated with any other. Suppose that I want to scratch
an itch in my left arm with the tip of the middle finger of my right hand.
Both A locations have B locations recursively specified as above. Each of
those recursive specifications will relativize the B location to the respective
shoulder. Thus, all that is needed for those B locations to be fixed
Somatic Proprioception and the Bodily Self 157
relative to each other (and hence for me to locate the itch in my arm with
the middle finger of my right hand) is a specification of the position of
each shoulder relative to the other.
This account remains faithful to the phenomenology of bodily experience.
An important part of the phenomenology of bodily experience is,
as several writers have stressed, that bodily sensations such as pain are
presented not only as being at a particular point relative to other parts of
the body but also as located within a particular body part (Martin 1993,
Brewer 1993). This is captured very clearly by the distinction between
and interdependence of A locations and B locations.24 A bodily sensation
has a particular B location (relative to the body as a whole) only insofar
as it has a particular A location (within a particular body part), because B
locations are fixed on the basis of A locations. Moreover, the interrelation
between A locations and B locations captures the further phenomenological
point that body parts are perceived as belonging to the body as a
whole (Martin 1995). But explaining properly why this is so brings us to
what I have termed the descriptive dimension of proprioceptive content.
Earlier I contrasted characterizing the nature of a proprioperceived
event within the body (the descriptive dimension) with specifying where
that event is in the body (the spatial dimension). The first question to be
asked of the descriptive dimension of proprioceptive content concerns the
nature of the proprioperceived event. What is the direct object of proprioception?
The answer to this question can be read off from the understanding
that we now have of the spatial dimension of proprioceptive content.
The direct object of proprioception is the state of the body at a particular
location. In terms of A location and B location, this means that the direct
object of proprioception will be the state of the body at a particular location
in a given body part, which is itself located relative to the rest of the
body. Note one consequence of this, to which I will return at the end of
this section. The body as a whole features in the descriptive dimension of
proprioceptive content, just as it does in the spatial dimension.
The descriptive aspect of proprioceptive content is that the body at a
particular location is in a particular state. But what sort of state? It may
be helpful to consider the range of bodily states that feature in proprioceptive
content under the familiar headings of ‘quality’ and ‘quantity’.
The qualitative states are those familiar from the phenomenology of