The first objection he deals with is that SS is unbiblical. He goes to 2 Timothy 3:16-17. He actually tries to follow the logic though.
All Scripture is inspired by God and profitable for teaching, for reproof, forcorrection, for training in righteousness 16; that the man of God may be adequate,equipped for every good work 17 (NASB).
First of all, Scriptures are described by Paul as being “inspired by God.” The phrase “inspired by God” is translated from the Greek word “theopneustos” which is literally rendered “God-breathed.” By this Paul is communicating that the very writings were breathed out of the mouth of God. Further, the authority that Scriptures do have is derived from the verity that the very words were spoken by God.
Secondly, notice that Scriptures are “profitable.” No one in this debate disagrees about this statement. However, the text says that Scripture is profitable “for” one kind of thing “in order that” another kind of thing might be true. To put the matter formally, Scripture is profitable for x, in order that y. The variable x refers to “teaching, reproof, correction, and training in righteousness.” The variable y refers adequacy and equipping believers. It is the y that Protestants point to as a clear declaration in Scripture of its own sufficiency. Let’s look at verse 17 more closely.
Now many Catholics do accept the material sufficiency of scripture. This is as distinct from the formal sufficiency of scripture which would be needed for Sola Scriptura. But we don't believe it based on 2 Tim 3. It is just not there. It is not anywhere in scripture. You can argue for material sufficiency from tradition but then you have violated your own rule. Your task here is to show Sola Scriptura is not self-refuting.
I don't think the passage equates the something with scripture and nothing more. It says scripture is one thing that would do these things. It does not say it is the only thing or even the best thing. It is the only thing Paul has in view at this moment. He is giving scripture high praise. But he gives tradition high praise and the church high praise in other places.
You keep running away from the Sola part of Sola Scriptura. This is a good thing. It is the problematic part. We need an interpreter. The Sola part tells us we can't find one that is trustworthy. None that at least gets the basics infallibly right. Sufficient needs to mean that Sola Scriptura is at least workable. It would not imply it is best but it would be at least one possibility. But empirical evidence shows it is not workable. The interpreter problem seems to be way bigger than people are willing to admit.
How might a Roman Catholic respond?
However, there are a number of problems with this line of reasoning. Firstly, when Protestants say that the Bible alone is sufficient as a normative guide for Christians, we don’t necessarily mean that nothing else could be sufficient. For example, if Christ appears to a native in Africa who doesn’t have a Bible and reveals the truths about God’s kingdom, this might also be sufficient. So, when we say “Sola Scriptura,” we mean that the Bible, by itself and without the addition of anything else, is good enough as a guide to the Christian life. I don’t need to know what Christ revealed to the native in Africa, for the Bible is good enough for me in America. Yet, Protestants also urge that nothing else is actually sufficient, for nothing else has proved itself to be the authoritative voice of God.
The argument is the bible is "good enough". It depends what you mean by that. In some sense the Gospel of John by itself is good enough. Should we ignore the other books of the bible? We don't want to minimize our experience of God. We want as deep and as full a revelation as is available. We also want to avoid error.
When you say nothing else has "proved itself to be an authoritative voice of God". How does something prove itself? What is the standard you measure something against to see if it is the voice of God or not? Isn't it a matter of faith rather than proof? When somebody publishes a list of 100 biblical contradictions, are you surprised they found that many? I am not. I don't believe any of them are real but if you don't approach the question with faith you will find lots. Same with scripture and tradition. Does it require some faith to believe what they teach makes sense? Sure. Is it more faith than it takes to believe the bible alone makes sense? No.
So how does the bible prove itself? It doesn't. Sola Scriptura can't solve the canon question. Tradition flows directly from Jesus so it can be as reliable as it's source. Scripture was not written by Jesus. We need to believe some other revelation that tells us these books were inspired. When you try and describe what that is it sounds a lot like tradition.
Sorry if I seemed uncharitable. That was not my intent. I did think it was a bit much for you to compare your conclusions to the divinity of Jesus. But generally you have not been arrogant or dismissive so I should not have replied so smugly. I do think the lack of check and balances in the Sola Scriptura system is a problem. It gives people the choice between being arrogant or being wishy-washy. Catholicism lets you boast in Christ alone. That is in the church as the body of Christ and it's teachings. One can brag about them and not be prideful.
But secondly the context really shoots holes in his conclusion as well. When you examine the verses prior it becomes clear Paul is talking about the Old Testament when he mentions scripture. That is a devastating problem he does not mention.
14But as for you, continue in what you have learned and have become convinced of, because you know those from whom you learned it, 15and how from infancy you have known the holy Scriptures, which are able to make you wise for salvation through faith in Christ Jesus. 16All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, 17so that the man of God may be thoroughly equipped for every good work.
Randy, I appreciate your desire for the truth. I’m open to fair and balanced feedback. I look forward to that from you.