Reflection schema Recursive definitions also look circular, but they are not. I am pretty sure this can be done. I was told something to the effect that it was a fixed point of the hierarchy of theories
T' = T + (Ex)Prf_T(x, ⌜F⌝) --> F
T" = T' + (Ex)Prf_T'(x, ⌜F⌝) --> F
. . .
(don't quote me), or something like that. And that is perhaps somehow equivalent tp P8. Not sure what fixed point means in this context or how it can be constructed.
(BTW, I know the resulting system is inconsistent.)