Depends which frequentist you ask. From Aris Spanos's "A frequentist interpretation of probability for model-based inductive inference":

For those who can't access that through the paywall (I can), his presentation slides for it are here. I would hate to have been in the audience for the presentation, but the upside of that is that they pretty much make sense on their own, being just a compressed version of the paper.

While looking for those, I also found "Frequentists in Exile", which is Deborah Mayo's frequentist statistics blog.

I am not enough of a statistician to make any quick assessment of these, but they look like useful reading for anyone thinking about the foundations of uncertain inference.