‘Go back to your constituencies and prepare for annihilation’ is just one of the things that Nick Clegg won’t be saying at his party’s annual conference in Glasgow. I don’t know if Lib Dems do gallows humour, but if they don’t, I’m sure the rest of us can help out.

But before putting the boot in, it might be worth imagining what the last four-and-a-half years would have been like if the Coalition parties hadn’t come together.

There are those who insist that a minority Conservative government could have won a snap election in the Autumn of 2010. We’ll never know, of course. But what we do know is that when this country needed a stable government, the Lib Dems stepped up to the plate. Everything that’s been achieved since – the jobs-led recovery, welfare reform, education reform, police reform, decentralisation, the raising of income tax thresholds and the progress towards deficit elimination – has relied on the votes of Lib Dem MPs.

Yes, they’ve been an awkward and difficult bunch – but don’t forget that while Conservative poll ratings are currently down by about a tenth on 2010 levels, Lib Dem support is down by a catastrophic two-thirds. Faced with a disaster on this scale, you’d be awkward and difficult too.

So, whatever the provocation (and there’s likely to be some over the next few days) don’t let’s be beastly to the Lib Dems. And in the upcoming by-elections, don’t let’s be beastly to UKIP either – there’s been far too much of that already. As for Labour, fight them with the truth, not with the lies they’ll probably throw at us.

It is said that negative campaigning works, but it stinks of the kind of politics that the public is turning against. Whatever the short-term gain, there’s a price to be paid for it.

If you want to see what a political culture looks like when beastliness becomes routine, then modern-day America provides a sombre example. Writing for Bloomberg, Cass Sunstein surveys the rot:

“In 1960, 5 percent of Republicans and 4 percent of Democrats said that they would feel ‘displeased’ if their son or daughter married outside their political party. By 2010, those numbers had reached 49 percent and 33 percent. Republicans have been found to like Democrats less than they like people on welfare or gays and lesbians. Democrats dislike Republicans more than they dislike big business.”

This isn’t because Americans are getting more intolerant across-the-board. Many forms of prejudice are declining, but ‘party prejudice’ is getting worse…

“…infecting not only politics but also decisions about dating, marriage and hiring. By some measures, ‘partyism’ now exceeds racial prejudice – which helps explain the intensity of some midterm election campaigns.”

Sunstein describes some of the academic studies on which these conclusions are based, including this one:

[The researchers] asked more than 1,000 people to look at the resumes of several high-school seniors and say which ones should be awarded a scholarship. Some of these resumes contained racial cues (“president of the African American Student Association”) while others had political ones (“president of the Young Republicans”).

“Race mattered… But partisanship made a much bigger difference. Both Democrats and Republicans selected their in-party candidate about 80 percent of the time.

“Even when a candidate from the opposing party had better credentials, most people chose the candidate from their own party. With respect to race, in contrast, merit prevailed.”

The fact that Americans are now more likely to dislike someone for being red or blue rather than black or white is progress of a sort, but how much further can they go down the road of party prejudice before democracy itself is damaged?