116 Maarten Franssen
functioning item, or a poor specimen of its kind, shows behavior that is unlike what it is
supposed to do, or that is only capable of doing something that falls signifi cantly short of
what it is supposed to do.
Functioning well or poorly can be seen as (clusters of) objective positions on a scale
that has total lack of performance (the worst performance) on one end. What then is at the
other end of the scale? In this respect there is again an important difference between the
case of technical artifacts and the case of biological items. With artifacts we can often
describe an ideal token of a particular functional type while not a single actual token of
that type comes even close to that ideal. This is especially so for artifacts that are based
on new operational principles. Around 1900 it was fairly clear what people expected of
an airplane; it was clear, for instance, what the list of functional requirements of an airplane
should look like. All actual primitive airplanes were far removed from this ideal, however.
That does not necessarily mean that, for example, the airplane of the Wright brothers was
a poor airplane, although it certainly would not have been considered a good airplane just
by being able to stay in the air. Similarly, during the late 1930s and early 1940s, the few
people who were working to develop the jet engine had a fair idea what such an engine
would ideally be able to do, but at the same time all prototypes that were built disintegrated
or exploded within a few minutes. Evaluative judgments of particular devices are thus
partly based on the performance of other representatives of the functional kind but also
partly on the distance between the device’s performance and the (imagined) performance
of an ideal device.
In biology, an ordinal or quantitative scale for function performance is determined
completely by the distribution of actual performances, and even then it is often very diffi -
cult to come to a delineation of the typical or normal performance, as is shown by the
controversies concerning the defi nition of health and illness in medicine. It may be tempt-
ing to believe that natural selection will fi nd an optimum for the performance of any
function fairly quickly, and that once found, this performance sets a standard comparable
to the ideal knife in the case of technical artifacts. This, however, is completely dependent
on the timely occurrence of the right mutations and of the possibility of a mutation in the
fi rst place. The famous case of the peppered moth (Biston betularia) in the English Mid-
lands, where in the 1930s the light-colored standard form was replaced by a black mutant,
is a case in point. There seemed to be no reason to doubt the adaptedness of the original
light-colored peppered moth in the soot-infested woodlands around Manchester until the
black variety, which was evidently better camoufl aged on the darkened tree stems,
appeared.^17 However, if the mutation would never have occurred, would we have found it
lacking? Was the light-colored variety already poorly adapted to the current environment
before the black variety appeared? Would we have recognized an empty niche, waiting to
become occupied? But then why is an extension of the human visual sensitivity beyond
the 400 to 800 nm spectrum not similarly considered an empty niche, a level of adaptation
that waits to be improved upon? Should people not be able to smell better, hear better, or