Public reason liberals say that it is unjust or illegitimate to violate the public justification principle. The public justification principle holds that all coercive policies must be justified to the reasonable people subject to them, on the basis of values these people accept and evidence they possess.
While there are interminable debates about how exactly to interpret this idea, one thing I rarely/never see discussed in print is how big of a deal is it to violate the public justification principle. Suppose I grant for the sake of argument that it's wrong. How wrong is it? Can the PJP be trumped or overridden by other concerns?
I presume that this all depends on how coercive the policy is, how deeply it flies against reasonable people's values and evidence, and also the other effects the policy has.
For instance, suppose for the sake of argument that epistocracy violates the PJP. Estlund argues it does. I think it does not, but suppose he is right.
But suppose also that instantiating epistocracy would guarantee 40% more open borders, 40% freer trade, 35% more liberal political policies, and would reduce the number of Iraq-style wars by 1 every 30 years. That seems like a great deal! Even if epistocracy violates the PJP, the overall increase in justice and decrease in horrible injustice would make it worth doing.
I admit my intuitions are probably skewed, though, because I don't find the public reason framework all that plausible to begin with.