explanation of the mechanism which does the perceiving of all the active
symbols, if it is not covered by what we have described so far. Of course, a
"soulist" would not have to look any further-he would merely assert that
the perceiver of all this neural action is the soul, which cannot be described
in physical terms, and that is that. However, we shall try to give a "non-
soulist" explanation of where consciousnes's arises.
Our alternative to the soulist explanation-and a disconcerting one it
is, too-is to stop at the symbol level and say, "This is it-this is what
consciousness is. Consciousness is that property of a system that arises
whenever there exist symbols in the system which obey triggering patterns
somewhat like the ones described in the past several sections." Put so
starkly, this may seem inadequate. How does it account for the sense of "I",
the sense of self?
SubsystemsThere is no reason to expect that "I", or "the self", should not be rep-
resented by a symbol. In fact, the symbol for the self is probably the most
complex of all the symbols in the brain. For this reason, I choose to put it on
a new level of the hierarchy and call it a subsystem, rather than a symbol. To
be precise, by "subsystem", I mean a constellation of symbols, each of which
can be separately activated under the control of the subsystem itself. The
image I wish to convey of a subsystem is that it functions almost as an
independent "subbrain", equipped with its own repertoire of symbols
which can trigger each other internally. Of course, there is also much
communication between the subsystem and the "outside" world-that is,
the rest of the brain. "Subsystem" is just another name for an overgrown
symbol, one which has gotten so complicated that it has many subsymbols
which interact among themselves. Thus, there is no strict level distinction
between symbols and subsystems.
Because of the extensive links between a subsystem and the rest of the
brain (some of which will be described shortly), it would be very difficult to
draw a sharp boundary between the subsystem and the outside; but even if
the border is fuzzy, the subsystem is quite a real thing. The interesting
thing about a subsystem is that, once activated and left to its own devices, it
can work on its own. Thus, two or more subsystems of the brain of an
individual may operate simultaneously. I have noticed this happening on
occasion in my own brain: sometimes I become aware that two different
melodies are running through my mind, competing for "my" attention.
Somehow, each melody is being manufactured, or "played", in a separate
compartment of my brain. Each of the systems responsible for drawing a
melody out of my brain is presumably activating a number of symbols, one
after another, completely oblivious to the other system doing the same
thing. Then they both attempt to communicate with a third subsystem of
my brain-my self-symbol-and it is at that point that the "I" inside my
brain gets wind of what's going on; in other words, it starts picking up a
chunked description of the activities of those two subsystems.
Minds and Thoughts^385