For one thing, there are 37 of them, and most are very long! Just as it seems unlikely that a composer could write 37 full-length symphonies, it does not seem possible that one person could have written all those plays.
For another thing, he supposedly wrote comedies, tragedies, and history plays. Each one of these is a totally different type of story. How could one person be so good at writing all three types? It seems as impossible as a novelist who is good at writing mystery novels, but also writes great science fiction stories and biographies. What are the chances of that?
Finally, the fancy poetic language in the plays sounds like someone very educated wrote them. However, historians have determined that Shakespeare never went to college. He might have been smart, but he did not get an advanced education.
For all of the above reasons, Shakespeare could not have written all of the plays people think he did. He probably wrote some of them but had help from a well-educated friend or a
teacher. I wonder what that person would think today if he or she knew that Shakespeare got all the credit.
Paragraph 4 (For all the above reasons...) mainly tries to persuade readers that