They use texts of contemporary authors (they are convinced to know) who collaborated with Shakespeare!
(Such as Middleton, Fletcher , Chapman, Peele, Shakespeare)
Believe it or not, Prof.Ribeiro confirms , that
"There is by now evidence that about a third of the plays Shakespeare wrote, contained pieces that were not written by him"... and that
"...we keep enlarging the number of people with whom Shakespeare collaborated and that will help us understand better his creating writing process..." and that
"...we know now that Marlowe played an important role on Shakespeare becoming Shakespeare"
a) we have the ability to use texts that we know, who the writers of those texts are , and we can use that knowledge to classify texts, we don't know...
b) ...comparing the Marlowe profiles to some of Shakespeare's late plays where we know that Marlowe was not the candidate of those plays...
... When an individual utilizes another individual’s lack of information on a specific subject as proof that his own particular argument is right.
... When somebody asserts that a thought or conviction is correct since it is the thing that the general population accept.