Sir Tom Devine is Scotland's greatest living historian. No academic has done more to expose, elucidate and publicise Scotland's historic involvement with the Atlantic slave trade. In works such as Recovering Scotland's Slavery Past, he pointed out that Scots were just as implicated in the slavery business as the English.

So when I learned that Sir Tom had been accused of being a member of a “racist gang” I couldn't believe it. Yet, this allegation has been made by the Chancellor of Heriot Watt University, Professor Sir Geoff Palmer, a noted campaigner on human rights who is chairing a review into Edinburgh University's historic involvement with slavery. Professor Palmer had earlier accused another Edinburgh academic, Professor Johnathan Hearn, of the same offence.

To accuse Sir Tom of racism is so obviously defamatory and unreasonable you'd think no one in their right minds would make it, and no university (surely) would let it go unchallenged. Yet it has. As former Rector of Edinburgh University I urged Professor Palmer online to retract – without response. Instead, another Edinburgh academic has now leapt to demonise Sir Tom and Professor Hearn as “white scholars” defending racism.

When people say that the culture wars are a figment of journalists' imagination, tell them about Edinburgh University. It has become a toxic stew of bad faith, ignorance and libel since the crass attempt to “cancel” David Hume, Scotland's greatest philosopher, two years ago.

Principal Peter Mathieson seems unable to control the rabble who have abused and threatened staff members like the wellbeing expert, Dr Neil Thin, and the feminist former Rector, Ann Henderson. The University has now stood by while baseless accusations of racism have been levelled at current and former members of staff by the individual supposedly conducting an unbiased review of Edinburgh's racist history.

This row has arisen, perhaps inevitably in this age of teenage iconoclasm, over a statue. Specifically, that of Henry Dundas, Viscount Melville(1742-1811), the former Lord Advocate, that stands in Edinburgh's St Andrew's Square. How the old rogue must be loving all this celebrity two centuries after his death. If you look closely you can see a smirk on his stony face.

Following a petition condemning this A-listed monument, a plaque now informs us that Lord Melville was responsible for delaying the abolition of the slave trade 200 hundred years ago. This is true. He was an abolitionist, as were many Scots in his day, but he argued that the slave trade should be abolished “gradually”, meaning in a manner that did not harm British interests or the wealth of the merchants, financiers and plantation owners who benefited from the murderous trade. How many lives were wrecked by his 15-year-long delaying tactics is hard to say, but the numbers would be in the hundreds of thousands.

However, what the plaque does not say is that earlier in his legal career, Henry Dundas defended a runaway slave, Joseph Knight, in one of the 18th Century's most famous cases. Thanks to Dundas, Knight was freed from his forced indenture with the Jacobite, John Wedderburn. This landmark ruling in the Court of Session finally established that slavery was illegal under Scots law.

This is clearly part of the Dundas story and should be mentioned, along with his hatred of slavery, in any objective account of his life. His speech at the trial, quoted in the 1776 Caledonian Mercury, was an eloquent tirade against slavery, which he condemned as “unjust”, “immoral” and “villainous”.

Yet, Professor Devine has been vilified for defending a more rounded account of Dundas as cited by his colleague, Professor Hearn. It seems that merely to argue for the inclusion of historical fact can now expose academics to accusations of racism – arguably the worst slur short of sexual misconduct that can be made against anyone in university life. Many fellow academics are horrified, but are keeping stumm, afraid that they'll be next in the stocks.

Sir Tom needn't worry about his academic standing or reputation. Anyone who knows anything about Scottish history knows how significant he has been in educating Scots about their nation's involvement in slavery. But it is not Sir Tom we need to worry about. Less established academics are now terrified that they might transgress some racist boundary merely by investigating the past.

Yet it is not racist to tease out the complexity of history. It is what universities are supposed to do, not conceal inconvenient truths. What message does this send to young historians and students? That they must follow a precooked and prejudiced narrative to avoid being denounced? History rarely falls into a simplistic moral narrative.

Dundas, the “Uncrowned King of Scotland”, was undoubtedly a rank badjin as the cartoonist Bud Neill might have put it. He almost certainly enriched himself by using public money for speculation in the East India Company. But to conceal his defence of Joseph Knight involves a distortion of Scottish history. It is also counter-productive. Inadvertently, Professor Palmer has done more to publicise Dundas's role in ending slavery in Scotland than the “racist gang” he vilifies.

Professor Palmer seems to think the Knight case is insignificant, eclipsed by Dundas' parliamentary delaying tactics. Others have said he was just arguing a lawyer's brief in 1775. But we can't know that. James Boswell, biographer of the abolitionist Samuel Johnson, said Dundas gave one of the greatest speeches he had ever heard. The case was a pivotal moment in Scottish history.

Anyway, if it is argued that he made his thunderous denunciation of slavery out of expediency, you could equally argue that Dundas, as Pitt's gopher, was just doing what was expected of him in voting for delay. Dundas was never an ideological defender of the slave trade but an early abolitionist.

I hesitated to give this demeaning spat more publicity, but we really should know what is going on in our institutions of higher learning. Universities are funded by public money, lavishly in the case of Principal Mathieson whose salary is more than twice that of the First Minister. He should now stand up for decency in debate, or stand down.

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