The one sliver of optimism that – it has been claimed - we can salvage from the train wreck that is British politics is the fact that there is more scepticism about the claims made by our representatives in Parliament.

We are all now more alive, it has been said, to what philosopher Harry Frankfurt coined in 2005 as “bullshit” culture.  Nowadays, we’re told, parties will see their poll ratings slide by several points when even their paid-up members get a sniff of the stuff. Exhibit one: the recent slump in Labour Party support as activists got wind of Jeremy Corbyn’s true intentions over Brexit.

But the theory only goes so far: most of the time we only call out bullshit when it’s flowing from the tribe we loathe. Exhibit two: whenever Labour is criticised over the fact of widespread antisemitism within the party, the most common riposte is to deny it and attack the Tories.  

Enter Jewish moral psychologist Jonathan Haidt. His research has showed that our emotions and instincts are not separate to reasoning in our decision-making, but actually one of the drivers of the cognitive process. This means that while we often believe we have come to a conclusion in the same way a judge weighs up evidence, we are in fact more like lawyers, defending a position already dictated by our client (our instincts). Our political judgments are not immune: when we have political debates, we almost always defend a pre-decided position.

The explanation for the existence of this process, says Haidt, is that we have evolved to optimise our ability to dominate other tribal groups. Truth is relatively unimportant in evolutionary terms – it’s beating the other groups and consolidating ourselves as winners within our own group that counts.

This is absolutely not to say that truth is unavailable, merely to point out that we shouldn’t be so surprised when members of an opposing group fail to recognise reality when it is staring at them in the face.

 "We evolved for tribalism", a form of group-think, Haidt has said, that "evolved to help us manipulate each other and defend our reputations [and that of our tribe]. That’s why you can’t win a political argument with reasoning and evidence.”

The idea that we are wired to defend our own “tribe”, and defend our reputations within that grouping, has purchase at all levels of our political culture. First, and most obviously Twitter and Facebook culture has evolved along exactly those lines – echo chambers in which we generally gather ‘likes’ and ‘retweets’ to bolster our own personal reputations as we fight and shame ‘outliers’ to our followers.

But whole political movements, lobby groups and think tanks have organised themselves along these lines. Take, for example, the report released last week by NGO Amnesty International attacking companies such as Airbnb and TripAdvisor for listing Israeli property in West Bank settlements and East Jerusalem.

Amnesty has a poor record when it comes to Jews. Last December, in its large-scale study of the abuse of female politicians and journalists on Twitter, it failed to include antisemitic targeting of Jewish women. And in March 2015, a resolution at Amnesty’s annual conference “to campaign against antisemitism” was defeated, the only motion not to pass.

In such a context, it is hard – understandably so – for British Jews to see Amnesty’s report on West Bank settlements and East Jerusalem as anything other than biased, whatever injustices it claims to be highlighting.

How could an NGO manage to so comprehensively undermine its own credibility on Israel while simultaneously putting out reports on the Jewish state’s activities and maintaining its image as the paragon of human rights advocacy? Back to Haidt’s “reputation” mechanism. Amnesty has gathered itself a tribe which assumes that since it fights for human rights, it cannot possibly ignore the human rights of any single group. Any examination of Amnesty’s actions will be based on that unexamined “truth”.

But, in this story, Amnesty was not the only group playing to its gallery. Israel’s response to Amnesty's attack on companies offering tourists room in Jewish homes beyond the Green Line made for depressing reading. Tourism Minister Yariv Levin said: "No force in the world will change the simple historical truth - the Land of Israel belongs to the Jewish people. We will fight this despicable antisemitic decision. No one can boycott Israel or parts of it."

That’s right – he called the settlements and East Jerusalem “parts of Israel”.  That is not a moderate position – it flies in the face of what most supporters of the two-state solution say is the only viable way out of the conflict - and reflects the fact than Mr Levin will soon be fighting for his seat in April's Israeli election in what has become a nationalist race to the bottom.

The river of bullshit is deeper and wider than we think.