The step from Linnean systematics to cladistics (in biological systematics) is a step from nominalism to realism – a step from classifying reality to classifying classification.
The problem with Linnean systematics (ie, nominalism) is that it is ambiguous in relation to reality (ie, there are always at least two ways to do the same thing, or the axiom of choice), whereas the problem with cladistics (ie, realism) is that it is ultimately paradoxically contradictory (ie, that every system is paradoxically contradictory, as shown by Russell’s paradox).
There is thus no single both consistent and unambiguous system of classification, but just a turn-around between systems that are ambiguous in relation to the classified and systems that are paradoxically contradictory. The place where such an imaginary system ought to be is actually a turn-around, or a step, that is, a void. This fact should not, moreover, come as a surprise, since a system consisting of both locations and routes (between locations) can never fuse locations and routes both consistently and unambiguously. If it could, then there wouldn’t be any difference between location and route, which the system on the contrary implicitly presume by distinguishing them. We simply can’t both eat the cake and keep it.