Principios de Taxonomia

3.2
Class Formation and Relational Group Formation
3.2 Class Formation and Relational Group Formationj47
Organisms can be grouped in two fundamentally different ways. First, one can sort
according to trait resemblance, which is a class formation and a grouping based on
equality of types. Equal- or similar-looking objects are combined into a group,
resulting in the problem of whether groups like these are accurate because humans
can, of course, choose the traits they want and form groups that are based on any trait
resemblance (Devitt, 1991). Given a number of objects that have a mixture of several
traits, one can form a considerable number of different groups from that number of
objects, depending on which trait you select to base group formation on. Because it is
certainly possible to combine objects according to the purely subjective criteria of
human preferences, it is at least feasible that groups are formed that do not exist
outside of the human need for sorting.
Groups of objects with equivalent traits are called classes (here, the concept of
a class should not be confused with the usage of the word class as a category in
taxonomic classification alongside the categories of genus, family, order, etc.). Another
alternative consists of combining objects into groups if the single objects are
bound to each other; this means not simply bonds that are generated by conceptualizations
in the human brain but objectively existing links that would exist even if
there were no humans. Group formations such as these are not based on similarities
in intrinsic traits but on relational cohesions. These formations are based on the
organisms relationships to each other; for example, a red item belongs to the class of
red objects because it has the property of being red. A neighbor, however, is a
neighbor because he possesses a certain relationship to the person of reference, not
because he possesses a certain intrinsic trait that would make him to be a neighbor.
Class formation and relational group formation are two entirely different grouping
methods that are based on different conceptual laws thus they may not be mixed
(Ghiselin, 2002).
These insights are of enormous importance for taxonomy because taxonomy is
group formation, and it is critical to ask from the beginning whether individual
organisms are sorted and grouped according to traits or whether they are combined
into a group because they have certain ties to other members of the group.
The traits by which class formations can be made are intrinsic traits, meaning
those that the organisms carry entirely within themselves. Every member of the
group carries all components required to make it a member of its group in and of
itself; a second red object is not needed to make the statement that a particular red
object belongs to the red group. Upon seeing a single object that is red, it is immediately
clear that it must belong to the class of red objects. To belong to a certain class,
it is sufficient to have the intrinsic trait that unites all group members. The members
must have this trait, but nothing else is required.
An entirely different matter is the relational group, in which the members of the
group must be cohesively or causally connected to other group members (Figure 2.5).
An additional object of reference is always required in relational grouping. Upon
seeing a single man, you immediately know that he belongs to the male group, not to