IT'S an old line that shows that sick jokes go back a long way: "Apart from that, Mrs Lincoln, how did you enjoy the play?" Significantly, when MC Stephen Fry tried a verbose rehash of the gag at this month's Baftas, it was he who died a horrible death in the theatre.

No silence is worse than a celebrity-audience silence.

After Daniel Day Lewis's extraordinary feat of resurrection in the film Lincoln – hotly tipped at tonight's Oscars – it seems the murder of America's 16th president is almost as unfunny as it was at the time.

In the film, Day Lewis, along with director Steven Spielberg and screenwriter Tony Kushner, have de-monumentalised Abraham Lincoln's greatness, as hymned by Tolstoy, as carved on Mount Rushmore, as quoted from memory by millions of American schoolchildren. Set at the end of the 1861-1865 American civil war, which began when the South's 11 slave-owning states decided to break away and form a new Confederate nation, the film shows Lincoln struggling to pass the 13th Amendment abolishing slavery.

Lincoln has long held a special place in the hearts of Scots. In 1893, some 23 years after his assassination in a Washington theatre, Scotland was the first country outside the United States to erect a statue to him, in Edinburgh's Old Calton cemetery, in honour of the Scottish-born soldiers who died on both sides in the American civil war. One of them was the son of David Livingstone, who fought on the side of the Union.

Lincoln, the self-taught man of the people, humanitarian and liberator, idolised Robert Burns and could recite most of his poems from memory. Recent research has shown that the president's admiration for Scotland was mutual. One historian, Ferenc Szasz, wrote a book detailing Lincoln's professional and social ties to various Scots émigrés, as well as his intellectual debts to the transported traditions of the Covenanters and Scottish Enlightenment accrued during his grim frontier upbringing. According to Szacz's book, Abraham Lincoln And Robert Burns: Connected Lives And Legends, Burns's poetry provided the themes and rhythms that gave Lincoln's oratory their enduring power.

Four years after the president's Good Friday martyrdom, his widow, Mary Todd Lincoln, fulfilled their shared ambition by touring Scotland, where she visited Burns's cottage and "sighed over the grave of Highland Mary" in Greenock.

Lincoln, the icon of modern democracy, also lives on in modern Scotland. Earlier this month, the Scottish Government quoted him in their proposal for a written constitution for an independent Scotland, claiming that this document could be, as Lincoln described the US equivalent, "a rebuke and a stumbling block to the very harbingers of re-appearing tyranny and oppression".

Unionist commentators saw irony in the invocation of a champion of the US's federal union in this context, proof that history plus politics can be a volatile combination. But the reference was well-founded. Lincoln, as was said at his deathbed, "belongs to the ages" and not to either side of the current Scottish debate. He is as neutral as current US ambassador Louis Susman declared himself to be in Edinburgh last week.

In fact, the civil war, with the defence of slavery at its root, offers no more parallels with Scotland's peaceful, mutually-agreed constitutional test than does George Washington's rebellion against the British which gave birth to the US. This does not mean, however, that the 16th president has no lessons to offer contemporary Scottish politicians. In the film, Day Lewis's Lincoln demonstrates his genius for principled compromise and higher vision, as well as his mastery of the low-down and dirty work of getting votes in the bag. And although the stakes were high during the civil war (750,000 died in the conflict), the good humour and generosity of spirit made possible by the depth of Lincoln's conviction in his cause were admirable. These are qualities missing from Scotland's increasingly sour constitutional debate, where

the First Minister can be branded a "liar" in Parliament, and where so-called CyberNats post abusive messages about academics whose research casts doubt on the case for independence. Scottish parliamentarians could learn from Lincoln's humour, an aspect beautifully captured by Day Lewis. He made jokes that are funny for their own sake, a world away from the mirthless needling that passes for Holyrood humour.

But as the film shows, the politics of mutual abuse flourished in Lincoln's day. And if the great lawyer-statesmen himself were to visit contemporary Scotland, he would surely see past all that to approve of a referendum process that was conducted peacefully and by mutual agreement. He believed, after all, in the "sacred right" of "any people anywhere - to rise up, and shake off the existing government and form a new one that suits them better". A legal plebiscite that tested the strength of the desire of Scots to "rise up" and vote to secede from the United Kingdom would have chimed with the idea of "people's government" that Lincoln's career did so much to advance.

No such legal or political mandate was achieved by the rebellion of the slave-owning South that Lincoln opposed. The Confederacy's armed route to attempted independence, although cast by its propagandists as a popular war of resistance, was based on a complex charade of democracy, relying on votes for state-wide secession conventions that did not offer a yes/no choice.

According to Paul Quigley, American history lecturer at Edinburgh University, the decision to form a new nation might not have had majority backing throughout the South, even in a whites-only poll.

However Old Abe might fancifully be imagined to regard modern Scottish democracy, his affection for Burns's homeland was, in reality, tested during the civil war. This was despite the strong abolitionist tradition here. When Harriet Beecher Stowe, author of the anti-slavery novel Uncle Tom's Cabin, visited Edinburgh in 1856, she was fêted by huge crowds. Support for the Union against the Confederacy was the intuitive choice of religious Scots, and leading American emancipationists, including the African-American Frederick Douglass, regularly made Scotland the first stop on any European lecture tours to raise money for the Union cause. Douglass was just one American participant in a public campaign which exhorted members of the Free Church of Scotland to "send back the money" elicited from supporters in the southern states to support their breakaway ministry.

But of more significance to Lincoln was that much of Scottish business – including the owners of the Glasgow Herald newspaper – was firmly pro-South. As revealed in Eric Graham's book, Clyde Built: Blockade Runners, Cruisers And Armoured Rams Of The American Civil War (2006), Scottish shipyards, then at the cutting edge of marine technology, built the only fast steamers capable of evading the Union blockade of Confederate harbours and supplying the rebellion.

Graham details the vast fortunes being made by Clydeside shipbuilders and brokers building ships to beat the blockade. At the height of this boom in 1864, Warner Underwood, the US consul in Glasgow, complained that 27 Clyde yards were employing 25,000 men and boys building no fewer than 42 large blockade runners. Early 1860s Scotland was the scene of a cat-and-mouse game between Confederate agents and Federal spies, the latter operating from a safe house in the sedate dormitory village of Bridge of Allan.

The cash rewards for the Scots involved in this illicit trade were phenomenal. The sum total spent on building and refitting runners up to 1864 was £1.4 million (about £140m in today's money) – one-third of which was pure profit.

Graham believes that the blockade runners accounted for no less than one-third of the vessels that ran the Union blockade – more than half the British-built tonnage. The South had few of the industries needed to equip and support armies of half a million men and acquiring modern (mainly British-made) weaponry was vital to the war effort.

It is never wise to back the losers. The Scottish industrial economy only narrowly escaped the dire consequences of this partisanship. The Confederacy's collapse in 1865 brought the wrath of the re-United States upon Britain, eventually taking the form of claims for damage to US shipping by British-built Confederate raiders, and a larger claim for the entire cost of the war following the pivotal defeat for General Robert E Lee's Confederate forces at the Battle of Gettysburg – plus 7% interest.

The US maintained that Britain's complicity in supporting the South made the country liable for a staggering £8 billion – equivalent in today's money to the cost of the 2008 UK bank bailout. Half of this sum could have been blamed on Clyde shipbuilders and their associates, although as with RBS and HBOS, the taxpayer would have had to pick up the tab. After much sabre-rattling, the issue was settled in 1877, more than a decade after Lincoln's death, for a mere £7.5m in reparations.

Shipbuilders were not the only Scots businessmen who cosied up to the breakaway Confederate nation offering enhanced trading opportunities, and promising to be a useful rival the upstart US. Nor was it exclusively an elite preference. Scots coal miners, unlike Lancashire cotton workers, were working-class supporters of the slave-owning South.

In addition to using our ships, guns and goods, Lincoln's enemies drew on Scotland's culture for ideological support. The South's morale was sustained by romantic 19th-century nationalist mythology partly derived from the novels of Sir Walter Scott. It is a notable coincidence that one gigantic symbol of this energising ideology, Stirling's Wallace Monument, opened two months after the siege of Fort Sumter, the opening battle of the civil war.

This moral support from Scotland's population was also related to the romantic idea of military chivalry, which equated the South's often brilliant soldiery with the fighting traditions of the Highlands. Many Victorian Scots made the link between the Confederate armies with those other glamorised underdogs of Scott's novels, the Jacobites, while the daring victories of Lee and Thomas "Stonewall" Jackson were won by quasi-guerrilla tactics overpowering stronger armies, offering Scots parallels with the victories of William Wallace and Robert the Bruce.

For the American South, romantic nationalism and chivalry were, of course, no more than sugar coatings on an economic system based on slavery, but they played a big part in causing the rebellion and keeping it going despite overwhelming odds. Many there (like Lee himself) despised slavery or came from places where it did not exist. They nevertheless died defending the homeland from what they saw as foreign invasion.

Reversing the historical telescope, modern Scotland's economic case for peaceful secession from the United Kingdom (defined as "formal withdrawal from a body") has some noteworthy echoes of the Confederate economic case. Both are underpinned by a valuable primary product: in the South's case "King Cotton"; in Scotland's, North Sea oil and gas.

Time travellers from Lincoln's day might also recognise the SNP's claim of economic disadvantage at the hands of an elite with different priorities from the would-be secessionist state. In the case of the American South, that elite was the rising Yankee industrial class and its lackeys in Washington, DC. For Scottish Nationalists it is the City of London fat cats, with their cronies in the Tory party.

Another similarity is that, like the Southern rebels – though obviously with vastly superior moral grounds – modern Scottish Nationalism has come increasingly to present independence as the only preserver of a threatened "way of life".

The cause in Scotland is to achieve a new settlement, to discard austerity and "reflect Scottish values of fairness and opportunity, and promoting prosperity and social cohesion", as Deputy First Minister Nicola Sturgeon puts it in the introduction to the Scottish Government's recent constitutional paper.

None of those virtues, of course, featured in the "way of life" that Southern propagandists constantly (and euphemistically) extolled. But in both cases moves towards a radically new political and economic reality comes to be dressed in small-c conservative terms; as the only means of preserving "the values we hold dear", as the Scottish constitutional document has it.

Lincoln, the supreme political strategist, might be intrigued at the same motivational technique being deployed by such different independence movements, in different centuries, with such opposite values.

Whether the Yes side or the No side wins next year's poll, Lincoln's ghost might repay his debt to his Scottish heroes and influences by inspiring our politics with his spirit of conciliation, "with malice toward none", with which he rebooted American democracy. So far neither David Cameron nor Alex Salmond is showing signs of Lincolnian qualities, but then again, no-one rated Lincoln until he was tested.