All classifications are the result of artifice, convention, and technique. Ants, for example, do not present themselves to us neatly sorted into natural species or genera distinct from other arthropods for naming on the basis of unequivocal observation. We observe, recognise, sort and settle on a grouping and naming convention. I will call these alternatives the continuum view , the partition view and the subset view respectively. According to this view, the aim of a scientific classification is to maximise the naturalness of classifications while retaining the conventional usefulness required to implement them in practice.
Generality is bought at the expense of accuracy.
A truly natural classification would imply that each specimen was a class of its own, nominalism in the context of taxonomic classification. Since biological objects are generally unique in the array of characters they possess, some degree of abstraction, or ignorance of certain sorts of traits, is required in order to group them. This, I suggest, is the ruling conception of classification in scientific practice. The partition view is something of a strawman position, although some do seem to think that there is a fuzzy boundary between the two sets, and that some classifications are either entirely artificial or entirely natural. The subset view assumes that from a heuristic perspective, there is always some element of convention in a classification, but unlike the continuum view, it allows some classification schemes to be entirely conventional.