The property of being identical, or having the same physical properties, in all directions. (noun)
Examples of word isotropy
(Anisotropy is the opposite of isotropy, which is the condition of having the same value when measured from different directions.)
Put in slightly different terms: isotropic and Quinean processes are global rather than local, and since globality rules out encapsulation, isotropy and Quineanness rule out encapsulation.
Both isotropy and Quineanness are features that preclude encapsulation, since their possession by a system would require potentially unlimited access to the contents of central memory, and hence cognitive penetrability to the max.
It is possible that statistical isotropy/homogeneity is violated at very high significance in some specific fashion that does not correspond precisely to any of the particular observational effects that have been searched for, but that would stand out dramatically in a better-targeted analysis.
There is another important motivation for studying deviations from pure statistical isotropy of cosmological perturbations: a number of analyses have found evidence that such deviations might exist in the real world.