Last Thursday afternoon, the MP Jo Cox was murdered on the streets of Yorkshire, while out and about in her constituency, meeting the people she represented and listening to their concerns.

The wider debate about Jo’s killer’s motive – the extent to which he was acting alone, or linked to a wider movement – will rage on, and will not be easily settled. But one deeply worrying thing about her death could be said with certainty almost immediately: she was killed because she was an MP.

Jo Cox was killed because she had chosen a life of public service, and was therefore seen as a legitimate target. That’s a horrible thought.

It’s a truism in the internet age to say that people have become desensitized to the consequences of their actions when those actions take place online. Remove the eye contact, the personal connection, from an interaction, and otherwise mild-mannered people can say the most offensive and extreme things behind the comfort of a pseudonym and an avatar. Public figures in particular are ‘fair game’, as if several thousand followers and Twitter’s blue tick of verification means you can’t be hurt by awful things being said to or about you.

But what if that isn’t the end of the process? What if that desensitization starts leaking back into real life and – to some people – those in the public eye carry the protection of that blue tick with them wherever they go? They deserve it (and ‘it’ can be so, so much worse than 140 characters of vile abuse) because they have put themselves in that position, or so the logic goes. What if online forums and comment sections aren’t the final resting place for awful thoughts that no one would dare give voice to in real life, but instead a breeding ground for those thoughts to become actions?

All of this matters because the contempt with which politicians are currently spoken of is breathtaking. They are viscerally hated by large sections of the public. And it seems to be getting worse.

What is so sad is that this chimes so little with my personal experience working with politicians. Almost without exception, every MP or MEP or councillor I have ever met – from all parties – has gone into public service for the right reasons. They have chosen a path that involves long hours, hard work, intense public scrutiny, and incredibly difficult moral choices when many of them could have done something less all-consuming for more money. They are trying to do the best they can, according to their own values, every day.

But we have lost sight of all of that. Elected politicians are seen as grasping, venal, self-interested megalomaniacs. Unelected civil servants are seen as unaccountable, manipulative pen-pushers stitching up a system that works for them and no one else.

Those attitudes matter. Not just because the people on the receiving end of that abuse are human beings, with real feelings. Not just because we cannot hope to recruit a new generation of MPs or civil servants if that is how the profession is perceived. But because little by little they chip away at the contract between the government and the governed, until those unspoken ties – the ones that say “we put our faith in you to look after us” – start one by one to disappear. And when they go, we are in real trouble.

I’m not naïve. I know that significant responsibility for the way things are rests with politicians themselves. Too often, MPs and others have said the short-term, expedient thing to get them over the line in a single election, without thinking about the cumulative impact that has on the collective consciousness.

Again, that goes for all of them – be it a Labour party narrative that suggests anyone who ever votes Tory is fundamentally evil; a Conservative election campaign built on the suggestion that anyone who finds themselves out of work is a “skiver”; or the SNP turning a blind eye to virtual and physical intimidation carried out in their name. If we are going to rescue politics and public service, then politicians themselves need to reintroduce into the public debate the values and the decency which so many of them embody in their day-to-day business.

The media also has a clear responsibility. One of the more heartbreaking things in the aftermath of Jo Cox’s death was hearing so many people say: “she sounded so wonderful; how come we never heard of her before?” Because journalists don’t write stories about MPs doing their jobs well until after they have retired or, too often, passed away.

Newspaper editors will tell ethics committees that they just give their readers what they want – that the demand is there for salacious gossip and they altruistically respond to it. But at the same time they are attracting advertisers by telling them that their newspaper is an organ of influence: that it has the power to shape debate, to change opinions and behaviour. The truth, as ever, is somewhere in between – which means that journalists and newspapers have a duty to give us a much better and fairer representation of public life than they currently do. They can’t just wait until something horrendous happens before they discover that some politicians were all right after all.

Finally, though, we as citizens need to look at our own role. If the newspaper editors are half-right, then we help to create the demand for stories that do down the role of government and public service as a whole. And those unpleasant, dog-whistle tactics we increasingly see at the tail end of political campaigns are a response to an existing public mood as much as they are an attempt to move that mood in a particular direction.

Democracy is a two-way street. We’re not passive; we are participants – and we have to participate in a civilised and respectful manner if we hope to elect politicians who will do the same with one another. That means taking the time to listen to those who try to tell us that situations are complex and that there may be no easy answer, instead of shouting them down. It means rising above the kind of petty ‘activism’ that sees MPs who voted against action in Syria labelled as “terrorist sympathisers” and those who voted for it sent photographs of dead babies.

We all – the politicians asking for our trust, the press which holds them to account, and the citizens who elect them – need to rise to the challenge that Jo Cox’s death presents to us as a democracy. And that challenge is so simple, so banal that it shouldn’t need to be repeated, and yet on days like this it feels like it has to be: we all need to start being nicer to one another.