It seems that ontological hierarchies can be divided into fundamental and non-fundamental hierarchies. A plausible non-fundamental hierarchy is, for example, the hierarchy of buildings ordered by height, which has the tallest building as its summit. A plausibly fundamental hierarchy is that of (causal) power, which has the most powerful being in reality as its summit.

However, it is difficult to get clear on what makes a fundamental hierarchy distinct from a non-fundamental one. Perhaps the difference is that the summit of a non-fundamental hierarchy can be explained and determined by something external to the hierarchy, while the summit of a fundamental hierarchy cannot. For example, human beings can determine what is the top of the hierarchy of buildings ordered by height. However, something without causal power cannot determine what is the top of the hierarchy of power. The actual summit of the hierarchy of power needs to be explained in terms of something that belongs to the hierachy itself.

All this points perhaps to other features of fundamental hierarchies, namely generality and (relative) irreducibility. Fundamental hierarchies seem to include a lot of things and seem to resist being made subhierarchies of other hierarchies. We can, for instance, reduce the hierarchy of fastest runners in Europe to the hierarchy of fastest runners in the world. But it its difficult to see what more fundamental hierarchy the hierarchy of goodness can be made part of.