"You're trying to shut down the debate!" is a common slur in modern politics. It's what you say to someone whom you think has no reasoned response to the points you're trying to make, and just wants to shut you up any way he can.
Just ask the UK Independence Party; they've been saying this for years, to anyone who will listen. UKIP see themselves as a party of rogue outsiders who are challenging preconceptions and standing up for 'ordinary people' by breaking down the closed ranks of a self-interested, cocktail-sipping metropolitan elite of professional politicians* who have lost touch with the struggles of the working men and women they claim to represent.
UKIP paint themselves as candid tellers of (often unpalatable) home truths - on immigration, housing, and the economy - and, most importantly of all, as the victims of some great conspiracy to try and shut them down. They believe that the 'mainstream media' (as much a part of the exclusive ruling elite as the politicians) are out to get them for the crime of being straight-talking and appealing to 'ordinary people'.
But the only people who are really trying to 'shut down the debate' are UKIP themselves; anyone who has the temerity to disagree with their flagrantly populist agenda (as the inestimable Janan Ganesh does with his customary elegance in Monday's Financial Times) is dismissed as 'out-of-touch'. If you criticise UKIP's arguments, that can't be because you've spotted a flaw in their reasoning, or even because you simply disagree with their stance - that must be because you are an establishment stooge who is frightened of UKIP's rising popularity. In the UKIP world view, there are no differing opinions; UKIP is the way, the truth and the light, and anyone espousing an alternative point-of-view is part of some great and sinister cover-up orchestrated by a self-serving political elite who are desperate to keep UKIP at bay.
By perpetuating the fallacy that 'they' (the other political parties) are 'all the same', and that UKIP are the only party standing up for 'real people' and their 'real concerns', UKIP are able to disseminate their message of prejudice and fear in mainstream politics like never before. Many commentators were keen to point out the similarities between UKIP's new election campaign posters (which, if not explicitly racist, at the very least prey on an ugly and divisive collectivism which stems from a primal fear of anything and anyone 'different' or 'unknown') and similar campaign material previously distributed by the far-right British National Party. But the difference is that the BNP have tended to be seen for what they really are by the great British public (as Dan Hodges points out in The Telegraph), while UKIP have built their façade of being a 'straight-talking party saying what the majority of people really think' by railing against a perceived 'LibLabCon consensus' and cashing in on the genuine frustration which many people feel with politicians in the wake of expenses scandals and sex cover-ups.
Whether UKIP really do represent the views of 'most ordinary people' will become clear at next year's general election; if they are as in-step with public opinion as they claim, their share of the popular vote will surely reflect this. But whatever their showing at the election is like, UKIP must at some point come to realise that politics isn't always going to be as easy as saying whatever you like, and brushing your critics aside every time just by denouncing them as tools of a conspiracy designed to keep you in your place. Eventually, UKIP will have to defend their policies on merit alone, and not by simply shutting down the debate and discrediting anyone who attempts to criticise them as 'out-of-touch'.
* UKIP are immensely fond of criticising 'professional politicians' - but what's the alternative? Amateur politicians?! Yeah, they sound competent…