The word “conspiracy” works much the same way the word “cult” does
to discredit advocates of a certain view or persuasion. Historians do not
use the word “conspiracy” to describe accurate historical reports.
On the contrary, they use it to indicate a lack of veracity and objectivity.* 

Is the Authorship Question a conspiracy theory?

The term conspiracy theory is frequently used as a pejorative to diminish or dismiss the authorship question. Stratfordians claim that anyone who doubts that the man from Stratford is the author of the works attributed to Shakespeare is guilty of perpetuating a conspiracy.

In the authorship debate, the word conspiracy is often used to explain why alternative candidates have been compelled to remain anonymous. For Mary Sidney, as a woman, it would have been inappropriate and indeed transgressive for her to publish original work for the stage under her own name. However, this did not need to be a conspiracy – in her case it is simply a practicality. 

We consider inquiry into the authorship question as legitimate. The moot court presided over by U.S. Supreme Court Justices (1987), the Boston Bar Association’s mock trial to determine genuine authorship (1993), and the establishment of a Masters degree in Shakespearean Authorship Studies at Brunel University in the U.K. lend weight to the validity of engaging in this debate.

The Mary Sidney Society believes that research and inquiry are worthy pursuits. Examination of the past illuminates our present and informs our future. Labeling these pursuits as advocating conspiracy theories diminishes legitimate historical and literary research.

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*Rebecca Moore, “Reconstructing Reality: Conspiracy Theories About Jonestown,” 
Journal of Popular Culture 36 (Fall 2002): 200–20.