Over at GreenBaggins, Scott tried to make an argument for an infallible rule of faith other than the Bible. He wrote: "The fact is that Matthew 16:18-19 and Matthew 18:18 teach that man and/or those men can bind or loose, not just sin, but whatsoever they choose." Let's consider this argument piece by piece:
"that man and/or those men"
Peter and the other apostles are gone. Francis, like his predecessor Benedict XVI, is not an apostle of Jesus Christ, he did not personally receive revelation from Jesus as they did, It is a leap to say that the apostles could do X, therefore someone who is not an apostle can do X.
"bind and loose"
Of course, "bind and loose" doesn't sound anything like "define dogma." It sounds more like freeing people from their sins or leaving people in condemnation for their sins.
"not just sin"
That sounds like Scott is saying, "sin and more." But Rome's teaching of infallibility is that Rome is infallible only in her doctrinal and moral definitions, not in her exercise of discipline. So, if it is "sin and more" and implies infallibility, then Scott has proved a point that is stronger than what Rome can adopt. After all, a Roman bishop exonerated Pelagius (and then later condemned), a Roman bishop condemned Athanasius (and then later exonerated), and let's not even get into the trial of Galileo.
"whatsoever they choose"
In Roman Catholic theology, the definition of dogma is (officially) not arbitrary. For example, CCC 86 states:
“Yet this Magisterium is not superior to the Word of God, but is its servant. It teaches only what has been handed on to it. At the divine command and with the help of the Holy Spirit, it listens to this devotedly, guards it with dedication, and expounds it faithfully. All that it proposes for belief as being divinely revealed is drawn from this single deposit of faith.”Of course, I acknowledge that in practice the power is arbitrarily exercised (contrary to CCC 86), but this is just an internal inconsistency.
Likewise, to be precise the text does not mention choice, it just states that what is bound on earth will be bound in heaven and what is loosed on earth will be loosed in heaven.