PSacramento:
" there is no concrete evidence that Mark did NOT write the original gospel attributed to him. "
You've just made a fallacious argument. It goes like this: "Prove that that the invisible man isn't there." This argument reworded comes out like this: "There is no evidence demonstrating that the invisible man isn't there." If one uses the proof that no one can see him, then that seems to reinforce that the man is indeed invisible and therefore must be there. That is called a logical fallacy. Here's how it goes:
14. False Burden of Proof
In order to have a worthwhile argument, if you make a claim, you have the burden of proving it. This is the simple premise behind the false burden of proof fallacy. This fallacy occurs when someone makes a claim, and then says that because his/her opponent lacks evidence to the contrary, the claim is therefore correct or valid.
For example, say that Paul says, “Little invisible green men are living inside my brain and telling me what to do. You can’t prove me wrong, so therefore I’m right.” Unfortunately for Paul, this line of reasoning is flawed. If you make a claim, and assert it as true, you can’t then shift the burden to the other party and make them prove otherwise. This is why plaintiffs have the burden of proof in court–they’re the one(s) asserting the claim.
A good general rule for intense rational argument: if you can’t prove it, don’t assert it.
http://www.electrogent.com/2012/09/argue-like-a-man-understanding-logical-fallacies-part-5/
It is an argument, but it's an erroneous argument. Beyond that, in your reference link (http://www.abu.nb.ca/courses/ntintro/mark.htm) you don't seem to investigate very deeply. First, the site states that there is no internal evidence to support Mark wrote Mark. Secondly, it points to affinities of spoken Greek, which Mark (by any measure of the time) most likely did not speak. Thirdly, that there are hints of Semitic syntactical grammar only means that someone with some Semitic influence might have influenced the document. Still, there's no information regarding why a man who was likely illiterate could have authored. Fourthly, the vividness of the account may suggest the enthusiasm of an eye witness. However, it can also suggest the craftiness of a very good teller of tales, the same vividness used by novelists, the same vividness used by a dramatist. Those factors are just as valid. Fifthly, the inclusion of Eusebius as a reference merely establishes that someone heard what someone else (Papias) heard. But if you look deeper you will find that " Eusebius calls Papias a man of small mental capacity."(http://en.wikipedia.org/wiki/Papias_of_Hierapolis) He didn't trust him. So, if you're going to believe an account, maybe you should believe Eusebius and realize that Papias was full of crap and tended to exaggerate when talking about what Mark and Peter did. Finally, the site you referred to notes that Mark has earthier style, less literary. That is true simply because Mark is considered the earliest gospel written. That gave other writers a chance to review Mark and deploy other gospels around it.
