I need only consider their conclusion: rational disagreement is possible.

I need only consider their conclusion: rational disagreement is possible. If so, then it follows that when I recognize that my epistemic peers disagree with me on some issue, sometimes I may still justifiedly believe that my view is true.

(I take it that believing that X and believing that X is true are the same thing.) In addition, depending on one’s view of rational disagreement, this might mean I am justified in believing I am justified, and perhaps even in believing that my peers are justified in having similar attitudes toward themselves.

So, what rational disagreement arguments deliver us, at the end, is something like B: ‘Even though my epistemic peers disagree with me on this issue, I am right, they are all wrong, I am justified in holding my view, and they are also justified in holding theirs.’ If I am justified in holding B, then insider scepticism is defeated. I am not required to become an agnostic and a sceptic. However, notice that B is not what truth-seeking, error-avoiding agnostic wants.

She comes to philosophy hoping to obtain true answers to philosophical questions while avoiding error. If rational disagreement is possible, then philosophical inquiry can get her justified belief in various philosophical doctrines even in the presence of disagreement, but that was not what she asked for. A justified belief that one has the truth on some issue is a great thing to have - I certainly would like to have that - but it is a poor substitute for bona fide truth.

The truth-seeking, error-avoiding agnostic is not interested in this substitute. She might be impressed to learn (depending on what the standards are for rational disagreement) that many or perhaps all philosophers are justified in their beliefs. With some good fortune, we might discover that all actual philosophical disagreements among members of the APA are reasonable ones, and so no philosopher must do any belief revision or become a sceptic.

However, this still does not give the truth-seeking, error-avoiding agnostic reason to become a believer. She wants a greater than not chance of getting true beliefs about most philosophical issues. Even a 100% chance of getting a justified belief that one has the truth about philosophical issues or (more simply) a 100% chance of getting justified beliefs about philosophical issues will not motivate her, because there are not the same things as a true beliefs about most philosophical issues.

They are poor surrogates.