The first one can be found here.
OPC Elder: Hi. I've heard that you've been saying that we have to choose between Reformed denominations, because separated denominations reject each others' de jure legitimacy and authority, and that you think the denomination we should join if possible is the Free Presbyterian Church of Scotland.
Frank: Yes, that's correct.
Elder: But that is not the Reformed point of view. We do not say that only one denomination is the de jure, legitimate church. We hold, with the Confession, that there are many churches, more or less pure, which are all parts of the visible church of Christ. There's the OPC, the PCA, the RCUS, the RPCNA, the FCC, and many others. All of these are legitimate churches, and the OPC fully recognizes the legitimacy and authority of all of them with all their church courts and officers. It is true that we are not unified in one denomination, but we have fraternal relations with them and recognize them as true churches.
Frank: But in a presbyterian system of church government, denominational separation necessarily implies a mutual rejection of de jure legitimacy and authority, because presbyterianism holds that the worldwide, catholic church is to exist in formal unity and that church power is collegial. The government of the presbyterate is universal, so that the elders and courts of the catholic church have a right and an obligation to govern collectively, subject to each other in mutually-binding councils. Although the OPC has fraternal relations with, say, the PCA, they still reject each others' legitimacy because they do not see themselves as subject to mutually-binding councils.
Elder: You are right that the OPC and the PCA are not in full communion with each other. We do not have full unity. But we do fully recognize each others' legitimacy. And we are working towards full union.
Frank: But you don't recognize the PCA's legitimacy, because you don't acknowledge yourself subject with them to mutually-binding councils. It is the right of church officers and courts to have collegial authority with the other officers and courts of the church. By denying the PCA officers and courts this right, assuming you have not rejected presbyterianism and that you are treating the PCA justly, you are denying their legitimacy and authority as de jure officer and courts (though not their de facto status as a true manifestation of the Body of Christ, however illegal). The only alternative to this is an embracing of a form of independency or congregationalism, where there is no recognition of universal collegial authority in the presbyterate and individual churches function independently from each other with no mutual submission.
Elder: You are right that, ideally, the presbyterate is to function collegially, and that the lack of mutual formal submission between the PCA and the OPC is a symptom that we are not in full unity. However, you are conflating two things that need to be kept separate. Although we are not fully unified with the PCA at this time, we do fully recognize the legitimacy and authority of their officers and courts. These two things do not so much imply each other that you cannot have one without the other.
Frank: Actually, they do so imply each other. If the PCA officers and courts have full legitimacy and authority, then that authority intrinsically gives them a right to function together in mutually-binding councils with all other legitimate officer and courts. You cannot say in words that you acknowledge their legitimacy and authority while denying this in practice by not submitting to their authority by granting their right to govern with you as part of the universal presbyterate of the church. This is a contradiction. So which is it going to be? Do you grant the legitimacy and authority of officers in the PCA, thus recognizing their right to join with you in mutually-binding councils (and thus ceasing to be two separate denominations), or do you refuse to recognize that they have such a right and thus reject their legitimacy and authority?
Elder: Why do you have to put things in such a black and white way?
Frank: I only do it when the truth calls for it.
Elder: But don't we need to recognize nuances?
Frank: Yes, when they exist. To ignore a legitimate nuance is a to distort the truth. On the other hand, to make up a nuance that does not really exist is to distort the truth as well.
Elder: Perhaps we can say this: The OPC does not recognize the full legitimacy and authority of PCA officers and courts, but it does grant them a partial legitimacy.
Frank: Are you saying that the PCA officers and courts only have some of the rights and responsibilities of ordinary officers and courts?
Elder: Yes, something like that.
Frank: OK. So what rights and responsibilities do PCA officers and courts have, and what rights and responsibilities do they not have?
Elder: Well, they have a right to govern their own churches, but no right to join with the OPC in mutually-binding councils.
Frank: If they are not competent to join with you in mutually-binding councils, why are they competent to govern their own churches? Is the former function more important than the latter?
Elder: Well, no . . . but we can't stop them from governing their own churches. That is their business, and we are in no position to interfere with them. But we are in a position to grant or not grant them a right to join with us in mutually-binding councils that affect our churches as well as theirs.
Frank: Why can't you stop them from governing their own churches? Are not all churches subject to each other, so that an overarching governing assembly could discipline lower courts and officers if they do not adequately fulfill their responsibilities? Just because you do not grant their right to govern the church collegially with you, it doesn't follow that they are not subject to the higher courts of the church.
Elder: Well, yes, but we don't have the kind of relationship that would make this possible. They don't recognize the OPC courts as being over them.
Frank: They don't recognize OPC courts as being over them? Well, that's not the real question, is it? The real question is, Do the OPC courts actually have authority over them to discipline them?
Elder: No, we don't.
Frank: But in presbyterianism, the higher (or broader) courts always have authority over lower courts. You have excluded PCA officers from having any authority to join in the overarching councils of the church, but surely you aren't denying that there are such councils. That would be to deny presbyterianism for independency. And if there are such councils, they can discipline the lower, or subordinate, PCA courts and officers.
Elder: But they don't require discipline.
Frank: That answer sidesteps the previous question, which is whether or not they are subject to the OPC's discipline, but I'll follow where you lead for now, as I suspect we will soon return to the previous subject anyway. So you are saying the PCA officers and courts do not require discipline. Then let's return to one of my even earlier questions: Why do you allow them to govern their own (PCA) churches, but not join with you in mutually-binding councils? If they are competent for the former, wouldn't they be competent for the latter? And don't they join together with each other in mutually-binding councils--in their presbyteries and their own general assembly? How can this be lawful, and yet you won't let them join with you in mutually-binding councils?
Elder: Well, of course they govern their churches, and of course they join together in broader courts and councils. After all, they are legitimate de jure ecclesiastical officers and courts. They see themselves as having the same rights and responsibilities as officers and courts as we see ourselves as having in the OPC.
Frank: Are you saying that the PCA officers and courts view themselves as having full legitimacy and authority, and thus a full right to fulfill all the responsibilities of officers and courts of the church?
Elder: Yes, that's how they see themselves, just as that's how we see ourselves.
Frank: But earlier you were saying that you don't grant them full authority, but only partial authority. Are you taking that back now?
Elder: Well, yes . . . I mean no . . . I mean, it depends . . . Maybe we can put it this way: From the OPC's practical point of view, the PCA officers and courts have only partial authority, but from the PCA's point of view they have full authority, and the OPC, while practically granting them only partial authority, recognizes that they have full authority from their own point of view, and so the OPC shares their point of view that they have full authority, but it doesn't grant them full authority in practice from its own point of view . . . or something like that.
Frank: Why have we suddenly started talking like relativists? Is church authority an entirely subjective affair, so that it is only a matter of different points of view? "Church authority is in the eye of the beholder." Or is it an objective reality? Can we say objectively that some people have legitimate authority and other people don't, even if they might think they do?
Elder: Well, yes, certainly, church authority is objective, not subjective.
Frank: OK, well, then does the PCA have full authority, speaking objectively, or does it not?
Elder: Well, not practically from our point of view, but yes, they have it from their own point of view.
Frank: I thought we weren't going to be relativists. If the OPC sees PCA officers and courts as having only partial authority, and the PCA sees itself as having full authority, and the OPC is objectively right (and thus the PCA is objectively wrong), why doesn't the OPC discipline the PCA officers and courts for taking upon themselves more authority than is their rightful due?
Elder: Well, they aren't under our jurisdiction.
Frank: But they are under the jurisdiction of the whole church, for that is how presbyterianism works. So what is the overarching council that both they and you are under?
Elder: Um, well . . . Actually, let me rephrase what I previously said. Although the OPC does not practically grant PCA officers and courts the privilege of governing with the OPC in mutually-binding councils, we do grant that they have full, and not just partial, legitimacy and authority. They have just as much legitimacy and authority as we do in the OPC. After all, they also do not practically grant us the right to govern together with their councils either. The OPC is not better than or higher than the PCA.
Frank: So you do recognize the PCA's full legitimacy and authority?
Elder: Yes, we do.
Frank: Then why don't you acknowledge in practice their right to govern the church with you collectively in mutually-binding councils, as presbyterianism requires?
Elder: We're not in full communion with each other, and so we cannot grant them power over us.
Frank: Who gave you the right to deny the rights of other legitimate ecclesiastical officers and courts?
Elder: They don't have an intrinsic right to govern with us.
Frank: Yes, they do, if they have full legitimacy and authority. That's how presbyterianism works. It is independency to deny that de jure churches have the intrinsic and unalienable right, responsibility, and authority to govern collegially with all other de jure churches. You must either acknowledge their authority and legitimacy, and thus govern with them collegially, subject to mutually-binding councils, or you can deny their authority and legitimacy and remain isolated from each other in terms of authority, existing as separate denominations. Presbyterianism leaves you no other consistent options.
For more, see here, here, and in general here.