The far right has been defeated. Andrew Neil's interview with Ben Shapiro and Andrew Marr's with Nigel Farage have exposed both men as shifty, vacuous and evasive. Their support will therefore disappear. What took the might of the Red Army in 1941-45 has today been achieved by two ageing Scotchmen.

Or not. For one thing these episodes won't weaken the far right's resolve. Farage is playing the victim card. "We are not just fighting the political class, but the BBC too" he says. Sure, his opponents think his interview was a disaster but his sympathizers don't: Andrew Lilico called it his "best ever." Such reactions demonstrate the pervasiveness of asymmetric Bayesianism - that we interpret evidence to corroborate our priors.

If we're being honest with ourselves, many of our political views - by no means just those on the right - were formed sub-rationally. And as Jonathan Swift said, "reasoning will never make a Man correct an ill Opinion, which by Reasoning he never acquired." This is especially the case if the protagonists are debating in bad faith.

Now, many of you will object to this that whilst such interviews and debates might not persuade rightists themselves, they might help turn neutrals away from the movement. I'm not convinced, and not just because Marr and Neil are only watched by a handful of politics nerds.

One issue here is that defeating rightists in debate is like playing whack-a-mole; even if you knock one down, another pops up. It's generally agreed that Nick Griffin made a fool of himself on Question Time back in 2009, and sure enough he has since fallen into deserved obscurity (although the BNP did increase its vote in the following year's general election). But other far-right figures have replaced him, such as Stephen Yaxley-Lennon.

There's an analogy here with snake-oil sellers. Even when reason and evidence did show that a particular product was inadequate, customers did not shun snake-oil generally. They simply switched to other sellers instead. As Werner Troesken showed in a fantastic paper (pdf), demand was unaffected by failure.

A second problem is that we've no good reason to believe that people are swayed by fact and reason alone. We know that huge numbers of voters are ignorant of basic facts, which makes them credulous about all sorts of daft ideas. We know too that they are swayed by things other than rational argument, such as looks (though in fairness these are unlikely to win Mr Farage much support). Rationality doesn't just require intelligence. It needs immense self-discipline, which many of (not least me) just do not have - and in the case of politics, have neither the means nor incentive to acquire it.

Which means neutral observers - even assuming there to be such things - are prone to countless cognitive biases. A particularly dangerous one in this context is the mere exposure effect; the more we see or hear something, the more we like it. It's possible (pdf) then that Andy Dawson is right: "the blanket coverage [Farage and UKIP] have been afforded has directly led to the shifting of the political landscape in Britain."

What matters here is not just Farage's personal appearances on TV. It's also what gets discussed. The more time the BBC devotes to the concerns of the right - ethno-nationalism, anti-"elitism", Brexit and so on - the more normal people think such debates should be. And conversely, in crowding out other matters, such as the decade-long stagnation in productivity and real wages, these become fringe issues. The agenda matters. And merely debating with the right shifts the agenda onto their terms.

I fear, then, that the right will not be defeated by debate. We must instead pull out the roots of its support. It is surely no accident that right-wing populism has increased around the world at a time of economic stagnation. Reducing its support therefore requires an end to that stagnation. It won't be done by talk alone.