In a series of tweets before the show, Dr MacKinnon wrote: 'I will not participate in a discussion panel that takes them seriously and gives them a platform.
'Would you expect a black person to actively 'debate' a KKK member on civil rights? That's analogous to what you're asking me.'Because how else can this argument go forward, if you fail to argue your case on its merits?
And it's not quite as ridiculous an ask as you seem to think it is:
Daryl Davis, an R&B musician, has spent decades engaging with the Klan and has evidence he's helped turn hearts away from hate. Davis says he has befriended 200 klansmen over the years who have subsequently left the group. More than 40 of them did so with a simple gesture and a powerful symbol: they relinquished their KKK robes to Davis.If they can do it, when their opponents have actively murdered them, rather than simply pointed out biological reality, why can't you?
The BBC's editorial guidelines say that guests do not have the right to stop other panelists from appearing on shows or in discussions.Guidelines the BBC clearly feel are made to be broken...
The BBC said Dr William's invitation had not been withdrawn and that she had instead been asked to appear later on the show, according to The Times.
A BBC spokeswoman told newspaper: 'We invited Dr Williams to appear on the programme and after initially agreeing to join us at a later point in the show she subsequently declined. The offer remains open.'Weasel words. The only sort we are ever likely to see on this 'debate'.