There is no harder concept to convey in politics than the idea of two contradictory things both being true at once.

But how else to explain the conundrum that is Diane Abbott, who today has pulled out of both a Woman’s Hour election special and an Evening Standard hustings on health grounds? On the one hand, she looks increasingly out of her depth as a prospective home secretary. Monday’s toe-curling Sky interview – in which she gave every impression of having either not read or completely forgotten a reasonably significant recent report on counter-terrorism strategy in London – was only the latest in a string of excruciating media appearances that could arguably have been avoided by doing more prep. Crying racism or misogyny in the face of legitimate scrutiny merely cheapens the issue.

Diane Abbott pulls out of Woman's Hour debate due to illness Read more

Yet all that said, something about all this makes me uneasy. Politics is a rough old game for good reason, but there is a fine line between the exercise of democratic scrutiny and playground bullying, and in Abbott’s case things are getting just a little bit too Lord of the Flies. It’s hard to articulate quite when the line is crossed, but you know when it happens: a certain queasy feeling in the pit of the stomach, and a strong desire to look away.

The obvious answer to the obvious question – which is whether a floundering white male politician would be treated this way – is that it’s certainly happened in the past. Think Iain Duncan Smith in his last hunted days as Tory leader, when both the media and his own party treated him with gratuitous public cruelty; or a mortified Gordon Brown, near the end of his time in Downing Street, being asked live on television if he was secretly on medication. There have been unforgivable things said of candidates on all sides in this bitter, grudging campaign.

But the queasy feeling persists, all the same, that it is possible for a politician to be both sinner and sinned against; both flawed, and held rather harder to account for those flaws than others.

If Abbott were the sole weak link in a shadow cabinet of towering political geniuses, then singling her out for ridicule in the systematic way senior Tories are doing – Boris Johnson could barely wait to drag her name into a Today interview this morning, regardless of what he was actually asked – would be no great surprise.

But to be blunt, this is hardly the front bench even of Jeremy Corbyn’s dreams. Too many of Labour’s big beasts have either, like Sadiq Khan in London, found other fish to fry or else just refused to serve, leaving behind a fairly patchy coalition of the willing. How many budding David Blunketts, Mo Mowlams and Gordon Browns do you honestly see in among the Richard Burgons? Yet it’s Abbott who is consistently wheeled out as the embodiment of everything floating voters should supposedly fear from Labour; Abbott who is portrayed as somehow uniquely dim, unfit for office, ridiculous for even trying.

And two days from a general election, in a campaign run as tightly as Theresa May’s, that sort of thing does not happen by accident. Abbott is becoming the bogeyman of the 2017 campaign, deployed just as systematically as the idea of Nicola Sturgeon sneaking in through Ed Miliband’s back door was in 2015, after Lynton Crosby discovered what a visceral response it provoked among wavering Tories. The question is why campaign messages attacking Abbott seem to go quite so viral, quite so easily; why it’s Abbott’s name that is booed most enthusiastically at rallies of the Tory faithful.

Once a politician starts to lose their confidence, the nervousness only makes mistakes more likely

Much of the abuse she gets on social media is undeniably racist or sexist and she has had hate mail from cranks all her career. It’s likely that some – although obviously by no means all – of those enthusiastically sharing “gotcha!” interviews on Facebook are more interested in seeing a black woman publicly humiliated than in the niceties of the Harris report on counter-terrorism. The drip, drip effect on Abbott herself of knowing that there will always be a hostile audience out there just itching to pounce cannot be underestimated – once a politician starts to lose their confidence, the nervousness only makes mistakes more likely – but nor can the ethical challenges it creates for those around her.

Neither journalists nor political opponents should feel remotely obliged to give Abbott an easy ride just because of the prejudice she faces. To do so would be both patronising and a dereliction of professional duty, given that from Friday she could be in charge of the nation’s response to terrorist attack.

But both have a moral responsibility to be conscious of exactly why the audience is clapping, and scrupulous about not playing to certain galleries. This campaign is sailing just too close to that wind for comfort.