“I’ve never seen a Catholic around here use an actual valid Protestant source for their definitions.”
Well, I know I’ve done it in the past. I used the definition from CARM for instance not too long ago and that is not the only one I have used: http://www.equip.org/article/what-is-sola-scriptura/
And the discussion usually ends up like this: http://209.157.64.200/focus/religion/3283268/replies?c=69
or this:
http://209.157.64.200/focus/religion/3250227/replies?c=109
or this:
http://209.157.64.200/focus/religion/3216634/replies?c=106
“They either pull a definition out of their own nether regions, or they find a poor, misinformed ex-Protestant like the author, and get them to cite a mangled remembrance of the principle.”
Well, what you just said there doesn’t apply to anything I’ve ever done so what will you say now?
All the replies you post there show you don’t understand the doctrine. It doesn’t really matter what source you’ve posted a definition from if you just go and run with your own personal conception of what it is anyway.