When engaging Roman Catholic apologists one often encounters two claims: 1) Roman Catholicism is publicly verifiable, meaning that one can provide sufficient reasons for a nonbeliever to convert to Roman Catholicism (see here for a detailed discussion on this) and 2) that any conclusion concerning the type of church Christ founded that does not secure a means of certainty (as defined by Roman Catholicism) can be rejected prima facie. In this article I will examine whether or not one can consistently hold both of these claims.
It is a basic characteristic of proper argumentation that something cannot be considered public evidence for a position when the basis of its value as evidence is taken from its object—that is, from the position the evidence allegedly supports. By public evidence, I refer to evidence that one can accept as evidence theoretically prior to accepting the position that the evidence supports. Taking this definition forward, this means that for a Roman Catholic to present public evidence for one to convert to Roman Catholicism he must provide evidence whose value as evidence does not rely on presupposing Roman Catholicism. One cannot provide public evidence to a nonbeliever for Roman Catholic church authority with alleged evidence that relies on Roman Catholic church authority for its value as evidence. Otherwise the argument would be immediately circular and publicly inaccessible.
Given this, the Roman Catholic apologist who seeks to provide sufficient reasons for one to convert to Roman Catholicism must build a case without appeal to church authority. If any element in the body of evidence that the apologist thinks provides sufficient reasons to believe presupposes Roman Catholicism, then this body of evidence cannot provide sufficient public reasons to convert. The Roman Catholic has failed to prove his case to the public. When this is the case, the body of evidence is insufficient to prove the case; and if a Roman Catholic cannot provide a sufficient body of such evidence for another to convert, then Roman Catholicism lacks public verifiability. But let us suppose that the Roman Catholic thinks that he can provide sufficient reasons to believe apart from any appeal to church authority. To even attempt this forces a startling concession: if one claims that he can provide sufficient reasons to believe Roman Catholic church authority apart from any appeal to that church authority, then he is consenting that Roman Catholicism could be false. And if Roman Catholicism could be false—that is, it is possibly false (probability is irrelevant)—then Roman Catholicism cannot provide certainty. For if something is possibility false, then one cannot consider its alternatives impossible; and if alternatives are possible, one cannot be sure that one of those alternatives is not correct. Thus Roman Catholicism cannot ensure certainty.
Let me state this point differently. When one discovers the legitimacy of the question “what type of church did Christ found?” he has already decided upon quite a few truths: Jesus Christ was messiah, he died and rose again, he founded a church, and his commission apostles to spread a deposit of truth. These are prerequisites to the question and therefore must be determined prior to the question’s answer. To be in this “realm,” a realm without an answer to the above question, requires a method of determining reasons to believe based on various sources. This is the realm from which a Roman Catholic must extract sufficient evidence to provide the answer to the above question. If this realm, one quite apart from church authority, is the theoretical basis of one’s apologetic, then Roman Catholic apologists cannot ensure certainty. For to consent to this methodology is to consent to the possibility of alternatives. Thus Roman Catholics apologists, by the very act of attempting to provide sufficient evidence or reasons to believe apart from church authority, undermine what they consider to be their greatest advantage: certainty.
We can take this further. When a Roman Catholic attempts to provide sufficient evidence or reasons to believe apart from church authority, he is assuming what one could call a Protestant-like paradigm or method. As I argued in Section III of my previous article (here), Protestants are in the business of providing themselves and others reasons to believe apart from church authority. When a Roman Catholic does this he is consenting to the possibility of alternatives, which must include conclusions that preclude the type of certainty that they often claim is necessary. This means that the Roman Catholic cannot have any prima facie objection to any claim that contradicts the type of certainty that Roman Catholic claim is necessary. In other words, when another comes to a conclusion, using the same method Roman Catholic apologists use to provide sufficient reasons to believe apart from church authority, that precludes the type of certainty that Roman Catholics consider necessary, Roman Catholics cannot immediately reject it on grounds that it fails to meet the condition of certainty. One can reject such an alternative only on the grounds of a presupposed condition of certainty. But the method used by the Roman Catholic apologist already involves consenting to the possibility that such an alternative is possible, otherwise the Roman Catholic would be imposing Roman Catholic presuppositions into the method, and thereby failing to be in a position to provide public evidence for conversion.
I’ll state it differently for clarity. If one consents to the proper terms of providing sufficient evidence to answer the question “what type of church did Christ found?”, then one cannot limit the possible answers to this question with a presupposed answer to the question. One cannot limit the possible answers to this question by presupposing that the church must provide the type of certainty allegedly provided by the Roman Catholic Church. To do this would presuppose the answer to the question when the question is the matter at hand. Thus when a person comes to a conclusion that precludes the type of certainty Roman Catholics find necessary, a Roman Catholic must reject it for its content, not reject it prima facie for its methodological basis.
Roman Catholic apologists want to have it both ways. They will present evidence that they find sufficient to lead one to convert, yet when Protestants, using the same method, present evidence that they consider sufficient to lead one to convert it is rejected without consideration to its content but only for it methodological foundation. Again, Roman Catholics cannot have it both ways. They cannot hold to both (1) and (2) in the first paragraph above. Either you can present sufficient reasons for one to convert to Roman Catholicism apart from church authority and accept the legitimacy of the methodological basis of Protestant conclusions (meaning you cannot reject them prima facie for their failure to provide certainty) or you admit that you cannot provide sufficient evidence apart from church authority for one to convert to Roman Catholicism (an admission that you cannot legitimately enter public debate) and you continue to presuppose the requirement of Roman Catholic certainty when evaluating Protestant conclusions and thereby reject them prima facie. Take your pick.
 By “rejected prima facie” I mean dismissing the legitimacy of the position without reference to or consideration of its details and solely from the outset of encountering it for failing to provide a means of certainty.
 There is such a thing, in my view, as private evidence that support internal consistency of a position. This fails to be public because the evidence relies on the system for its value; it is not inherently neutral.
 Faith, in the Reformed Protestant conception, is not the means of learning God’s promises, but an act of “seeing” or understanding those promises already provided. It is an act of overcoming our finiteness and sinfulness to see things beyond us. See another post (here) for more on this.
 Roman Catholics often dance between these two depending on which is most effective for an issue.