[From Bruce Abbott (960911.1850 EST)]
Rick Marken (960911.1540) --
So when an object's characteristics are not the result of design or evolution
they have no function? What about the tastiness of salt? The coolness of the
ocean breeze? Those seem like nice, functional characteristics that are not
what they are as the result of design or evolution. Salt was not designed to
be tasty. Ocean breezes did not evolve to be cool.
The characteristics you describe _are_ the result of evolution, so they do
have function. Salt is tasty (in small amounts) because salt is required by
the human body if the body is to function well -- or, indeed, at all.
Larger amounts are not tasty because large amounts of salt ingested in a
short time-span can seriously disrupt the body's functioning, even kill.
Ocean breezes are not cool, they just have a certain temperature. They
_feel_ cool because the skin's receptors and the brain that analyzes their
signals interpret that temperature as cool under certain conditions. That
cool sensation feels pleasurable under some conditions because in the course
of evolution the sensed cooling effect of the breeze under those conditions
has tended to be associated with improved body functioning. Ocean breezes
did not evolve to be pleasantly cool under the conditions in which they are,
but the body and brain did evolve to interpret them that way under those
conditions.
The problem is that function _implies_ purpose (in the normal, which is
the PCT, sense). Characteristics of objects are functional to the extent that
they are the means to a particular end (purpose); a characteritic of salt is
functional to a person who has the purpose of enhancing the taste of food; a
characteritic of ocean breezes is functional to a person who has the purpose
of feeling refreshed, and a characteristic of wings is functional to an
organism that wants to perceive itself flying through the air. When a
purposeful agent is not present, all the "functional" characteristics of
objects are just there; they have no function at all.
Yes, function _implies_ purpose (in the sense of an end-state to be
achieved, as in your definition #1). The function of adipose tissue is to
store excess fuel in the form of fat, and to release it as required by the
body. It continues to serve that function whether it is your purpose to
lose weight or not, as so many dieters have discovered to their dismay. The
adipose tissue has no aim or intention to do so, and yet it serves this
purpose. The thick shell of a turtle has no purpose (intention), yet it
functions to help preserve the life of the turtle by resisting strong forces
that otherwise might tear the turtle apart. If we ask what the purpose
(end-state to be achieved) of the shell is, we find evidence to suggest that
its purpose is to protect the turtle from excessive damage when the turtle
is attacked. Whose purpose is it? No one's. Even if the turtle decided
that it no longer intended to be protected in this way, the shell would
stubbornly continue to serve its protective function, even though it had no
intention to do so. The purpose of the shell is to protect, but there was
no one to intend this purpose; turtles just kept on evolving and in the
process, their characteristics changed over time in such a way as to meet
the turtle's requirements for survival and reproduction. The resulting
match between need and structure is identical to the match that results when
a good designer intentially chooses the characteristics of an artifact so
that the artifact serves the function the designer intended it to serve. As
such, we are completely justified in asking what function the structure
serves in the life of the organism, as if the structure had been designed to
bring about a given end -- to protect against damage, to facilitate flight,
to insulate against the cold.
Regards,
Bruce