Ayn Rand's measurement-omission solution to the problem of universals rests on the principle that everything is quantitative: *every* referent subsumed under *every* concept must be quantitative or else the referent would have no measurements to omit.
Aristotle included the concept 'quantity' in his list of basic axiomatic categories.
Question: where does the concept 'quantity' fit in the Objectivist hierarchy of concepts?
My answer is the concept 'quantity' is co-extensive with 'existence' and 'identity'. I call this point the Law of Quantity, and I have written an entire essay on it, expanding Ayn Rand's "Existence is Identity; Consciousness is Identification" principle as follows:
Existence is Identity is Quantity;
Change is Causality is Time;
Consciousness is Identification is Quantification;
Matter is Potential is Eternal;
Form is Actual is Temporal.
The essay (actually the first chapter of a planned treatise on metaphysics I have in my head) with a full explanation of these integration is available here: