The Catholic Church teaches that matters of faith and morals are contained in both Scripture and Tradition, that the interpretation of God’s divine truth is entrusted to the Pope, and that the Pope is prevented by the Holy Spirit from teaching error. Comparatively, some Christian churches look to the Bible as the only source of divine truth and the only authority by which “truth” can be interpreted. Accordingly, any teachings not found in the Scriptures are not part of God’s revelation, and that no person – including the Pope – has the authority to proclaim what is “true” doctrine.
On the surface, the simplicity of this Scripture-only (“sola scriptura” in Latin) approach appears reasonable. Besides, the only alternative would seem to be for a human being to hold this authority – a notion that many people find inconceivable considering mankind’s inclination to sin and corruption.
Furthermore, on the surface, “sola scriptura” is based on sound logic. In the study of logic, the conclusion of an argument is the position for which two or more premises are intended to provide support. A deductive argument is considered “sound” or “valid” if it is impossible for the premises to be true and the conclusion false. For example, consider the following logical argument:
Premise 1: A church’s teachings are based on those in the Bible.
Premise 2: The Bible’s teachings are true.
Conclusion: A church’s teachings are true.
This argument is based on sound logic. So, what exactly is the problem with depending on the Bible alone as one’s rule of faith? The problem might be best illustrated in the form of a question posed to Bible-only believers: “How do you know your church’s teachings are actually true?” In response, the believers may point to a passage in Scripture in an effort to “prove” that their teaching is genuine. However, the same question remains – how do they know their interpretation of that passage is correct – i.e., that they are “imparting the word of truth without deviation” (2 Timothy 2:15)? They might again be tempted to point to the Bible as support, which helps illustrate the circular reasoning inherent to “sola scriptura.” In an effort to break free from this conundrum, the believers may explain (even by ironically citing another Bible passage, in John 16:13) that the Holy Spirit guides their church to the correct interpretation of the Bible. However, digging a little deeper into the implications of this statement will further expose the problem of “sola scriptura.”
Many Bible-only churches claim to receive this unfailing guidance of the Holy Spirit. For example, the church of Christ down the road is confident its teachings are genuine because they believe their interpretation of scriptures is guided by the Holy Spirit. But the Baptist church across the street feels the same way about their own teachings. Which set of teachings contains the whole truth? While this point does not preclude the possibility of a Bible-only church’s teachings from being “correct,” it does call into question the certainty that most Protestant churches place on their ability to correctly extract Biblical truth.
In fact, “sola scriptura” provides no such certainty. At best, a member of a Bible-only church can only hope that their church’s teachings are correct. Yes, the Holy Spirit may be working to steer them toward truth, but there is no guarantee that the church’s positions on a given issue match those of the Holy Spirit. Consider our hypothetical question, “How do you know your church’s teachings are actually true?” The answer, simply and truthfully, is not only “We don’t know,” but “We can’t know.”
This is a far cry from the confidence initially inspired by the logic behind “sola scriptura.” On paper, the conclusion of “sola scriptura” does not require its supporting premises to be factually true in order to be logically sound. But in reality, the argument falls apart when trying to prove that a church’s teachings are in fact based on the Bible.
Why would God leave his people with a blueprint for interpreting and disseminating his divine truth as dubious as “sola scriptura?” Fortunately, He didn’t. Instead, God gifted to us a way of definitively knowing and teaching the fullness of His divine revelation. That gift is the infallibility of the popes. More on that in a future article.
For further reading, see “By What Authority? An Evangelical Discovers Catholic Tradition” by Mark P. Shea.
ProCatholic 
So, what I’m getting here is that the problem with “sola scriptura” is that you have no guarantee that a given church, despite a conviction that their interpretations are being guided by the Holy Spirit, is actually interpreting the Bible correctly and in line with what the Holy Spirit would actually intend. Makes sense. But the first line of this article states ” that the Pope is prevented by the Holy Spirit from teaching error.” I’m curious as to how you reconcile those two things.
I can’t see how Catholicism doesn’t leave you with the same “We can’t know” conclusion, just focused on a centralized power with a longer historical arm. How can Catholics be sure that the Pope is a conduit for the Holy Spirit if Bible-based Christians can’t?
I’m also not sure how you avoid going into a rabbit hole of circular logic. for example, you point out that it’s ironic that Bible-based churches interpret a passage of scripture to justify their interpretations of scripture. However, this cuts you off at the knees when it comes time to defend Papal infallibility. If you use a Biblical justification, you’re back to that “we can’t know” thing, where there’s no guarantee you’re getting it right (because, as you put it, the Baptist church across the street gets a different interpretation of the same text). But if you use a justification from papal authority, you’re committing the same ironic mistake as the “sola scriptura” fans and using a text to justify its own authority.
I am totally willing to wait til the next post if you were going to address all that, but you update your blog at roughly the same rate Amy and I do, so I figured I’d just ask ;).
(I’m not trolling. I’m genuinely curious.)