This is one of the two main points where Protestants and Catholics differ, the issue of tradition vs sola scriptura (the other being salvation on faith alone). Sola Scriptura does not state that the Bible is the only source of inspiration, nor does it hold that tradition does not have it's place (both are common misconceptions on both sides). It simply states that the scriptures are the ultimate authority on doctrine. That traditions, such as infant baptism or purgatory as examples, should be examined in the light of scripture to see if they are backed by scripture. Now I am not making the case for or against either of those positions, just pointing out that they are two 'hot-button' topics. It's one of the reasons the apocrypha is included in Catholic Bibles as there are some passages from 2 Macabees (if I remember correctly) that seem to lay the framework for support of purgatory. I think tradition (including oral) does have it's place in Christianity, but it should be verified against scripture. The old cliche about telling a story to one person in line and having them pass it on only to have the story mutate into something completely different by the time it gets to the end of the line is apropos here. In the scriptures however, we have the unchanging Word of God. Yes, translations change, but we can always go back to the original Greek, Hebrew and Aramaic.