Jacobi's suggestion - that the plays were a group effort - is particularly odd. If this had happened, why would all the credit be given to one person, and a middling actor at that? Why is there no reference anywhere to this literary conspiracy? Why did they operate in secrey so dark that it completely fooled everyone of their contemporaries, who all thought that William Shakespeare wrote them? Wouldn't just one of them have wanted the acknowledgement and fame that the co-author of Hamlet, Lear and MacBeth would be entitled to?
There is no evidence that Shakespeare didn't write the plays, but there is evidence that he did, from Greene's reference to 'Shakes-scene' in A Groats Worth of Wit (2) onwards, but the most compelling reason for thinking that Shakespear wrote the plays is far more simple. It is easier, to my mind, to imagine the existance of on freakshly brilliant mind, than to imagine several such minds existing at the same time.
Also, who would be his collaborators? Shakespeare was far ahead of his rivals - there was no-one else writing for the stage who wrote like Shakespeare, apart from Shakespeare. Marlowe, even, was not writing like Shakespeare. Faustus was closer in spirit and theme to the Morality Plays than to MacBeth. Ben Johnson was caught up in fashionable ideas about the influence of elemental 'Humours' on the psyche - an silly, simplistic idea that can't describe Shakespeare's main characters. Shakespeare pre-empted Freud, for goodness sake. Do you think he was balancing Ichor and Phlegm when he created Hamlet? No-one but Shakespeare could have written the plays, because Shakespeare was too good to be more than one person at work. There isn't enough of that sort of genius to go round.
We wait, with interest, to see if Derek Jacobi will follow through on his convictions, and refuse to appear in any play attributed to hakespeare, unless his doubts abou tits authorship are made clear - "Derek Jacobi, starring in Someone-or-other's Julius Ceasar."
1 "Actors question bard's authorship," unattributed BBC article, 9th of September, 2007. (http://news.bbc.co.uk/2/hi/entertainment/6985917.stm)
2- "A groats worth of wit"by Robert Greene, (http://www.uoregon.edu/~rbear/greene1.html)