  The Partition Ensemble Fallacy was recently applied to claim no quantum
coherence exists in coherent states produced by lasers. We show that this claim
relies on an untestable belief of a particular prior distribution of absolute
phase. One's choice for the prior distribution for an unobservable quantity is
a matter of `religion'. We call this principle the Partition Ensemble Fallacy
Fallacy. Further, we show an alternative approach to construct a
relative-quantity Hilbert subspace where unobservability of certain quantities
is guaranteed by global conservation laws. This approach is applied to coherent
states and constructs an approximate relative-phase Hilbert subspace.

Quantum Physics