Hang in there with this. It starts off a little rocky, but there's a payoff:
No theory is truly falsifiable or rationally justified, because there is no ultimate commonly agreed standard of rationality or set of premises to adjudicate on whether a theory has been falsified. This would let theology off the hook, had Bartley not gone on to formulate his own nonjustificational approach, dubbed “pancritical rationalism.” The pancritical rationalist refuses to commit to any position and holds everything open to criticism—not just any theory that he adopts, but also the criteria for rationality and the premises from which he starts.
I believe that Bartley goes rather too far. Yes, our beliefs, including our most cherished theological beliefs, should be open to criticism, but that ought not to preclude our being committed to them—otherwise, intellectual and moral paralysis set in. Commitment ought not to constitute a retreat so much as a launching pad for further inquiry. As Michael Polanyi puts it in Personal Knowledge, “The principal purpose of this book is to achieve a frame of mind in which I may hold firmly to what I believe to be true, even though I know that it may conceivably be false.”
So, there you go. Maybe "agnostic" is a better term. I've read books about Polanyi, not that I could understand a word of them. Sounds like this quote is from a preface anyway. I probably couldn't get past the roman numerals.