Last week, Nigel Farage announced his ambition, not just to be David Cameron's "worst nightmare" but Ed Miliband's as well. The general perception among the progressive media appears to be that Ukip's increasing threat (aptly illustrated by the suspiciously timely resignation of Douglas Carswell) will be a net positive for Labour, making it more difficult for the Conservatives to win the next general election. This is a mistake.
All too often we see politics as being only about the next election. It's not. Politics is about the sort of nation we want. Winning an election is a means to an end. That end is the principles we support becoming the principles that govern our nation. Elections themselves are not defining moments but the inevitable products of public debates. They are won and lost in the collective consciousness, not at the ballot box.
Margaret Thatcher defined the public discourse. Although she herself lost office, every government since, including those comprised of her political opponents, has pursued policies based on the ideology she espoused. Voters view the world according to the paradigm which she established.
Here's an example: most good economists will argue that the financial crisis was caused by a failure of the (private) financial sector. Yet all economic arguments in our public debate are based on the premise that we must cut back on the state. We don't discuss the logic behind this; it's become an irrefutable "fact" of British politics. The "Private = good/ State = bad" paradigm is unsupported by history or economics but every political party conforms to it because it is the paradigm which defines our public debate.
To win elections but, more importantly, to see its principles realised, a political party needs to define the debate. Unless it can do so (as I have argued before) it will always be arguing according to its opponent's terms and thus will always lose.
Ukip may prove to be of short-term electoral advantage to Labour. In the long term, it will push the public discourse further to the right. Labour may be in power after 2015, but its principles will not. A party that is content to maintain power by implementing ideals that it should fundamentally oppose does not deserve to exist.
In the United States some liberals privately welcomed the rise of the Tea Party when it appeared that its effect would be to make the Republican party permanently unelectable. Instead American public discourse was pushed to the right. GOP establishment figures like Karl Rove were made to appear centrist and reasonable, while Democrats were forced to refight old battles on abortion and race.
If Ukip continues on the road to mainstream acceptance, how long will it be before progressives in the UK are forced, once more, to defend hard-won legislation on equalities, employment rights or the minimum wage? Rather than arguing for a better future, the left will be forced to devote all its energy simply to prevent it becoming worse.
So how should the left respond? It's tempting to mollify Ukip voters, acknowledge that they have real concerns about immigration or human rights, in the hope of winning them back into the fold. But history should teach us that pandering to xenophobes only breeds more xenophobes.
Ukip supporters do not have reasonable concerns. The basis on which most positions in support of Ukip are founded are factually inaccurate. Supporting Ukip requires believing things that are simply not true. Pretending anything else will move the political discourse to a place where reality is permanently eclipsed by provocation.
There are real reasons that Ukip voters feel disenfranchised and these should be addressed, but not in the way they are expressed by Farage and co.
In the 2008 election, Obama For America destroyed John McCain's credibility by focusing on the ludicrous positions of his running mate, Sarah Palin. Her most famous statement, "I can see Russia from my house", came from the lips of Saturday Night Live's Tina Fey. Palin's politics were absurd so she was effectively laughed out of office. Ukip should be treated the same way. A party that bases its electoral appeal on ignorance and xenophobia should be a punch-line, not an election contender.
The enemy of my enemy is not my friend. Labour needs to get serious about Ukip. But the only way to do so successfully is not to take it seriously at all.