(25) Shakespeare was Shakespeare : a tauto-logical failure:

Nobody would ask :  "Why Winston Churchill was Winston Churchill ?"

Many who do not feel  able to question Shakspere as the author of  Shakespeare's  canon, suffer from a  "logical" fallacy. It consists of a circular argument ("circular reasoning"), which occurs when the assumption to be proved is included as  proved and thus a premise to conclusion is derived from itself. 

Examples:
Shakespeare wrote a dedication to  Henry Wriothesly, the Earl of Southampton in his epic poem "Venus and Adonis", indicating that Southampton was the patron of Shakspeare from Stratford. The construct of  an identity between  a poet Shakespeare  and  the  person from Stratford  Shakspere is tacitly assumed, although this is yet to test. A speculation is presented as fact.

Such circular reasonings were used in the authorship debate in excess:
Shakespeare's comprehensive education requires, for example, that he must have visited the school in Stratford. But there is no evidence that the person from Stratford Shakspere has ever attended school, nor that he could ever write fluently. A question, put to the test, is from the outset accepted,  because "a necessary precondition".

You probably would comment the question: "Do you know the great literary works of Joseph Conrad?"  by asking : do you mean Józef  Konrad (Korzeniowski) ? -

With Shakespeare, this question seems to be resolved. Nobody would ask: "do you mean William Shakspere, the merchant from Stratford?