Calm down dears, as David Cameron might have said. The row yesterday over Diane Abbott's remarks about "white people" shines a light on not just British attitudes to race, but also on our ability to absorb and deal with controversy in the era of instant communication. The wisdom – or lack of it – shown by the MP for Hackney North and Stoke Newington, aka "leftwing" or "firebrand", has already been discussed enough. The only tuppenceworth I will add on that score is that she seems stuck in a time warp of 1980s clichés and lazy assumptions. If she had said what she had said in the pub, or more likely at a north London dinner party table, her interlocutors might have agreed with her, challenged her or castigated her. Then they would have poured themselves a glass of chardonnay and moved on.

What is more discomforting was the hysteria that surrounded Abbott's tweet. Twitter is used for differing reasons. I relish looking at it several times a day to find out what is being said and written. I find it useful to see what free expression events are taking place and what organisations in the US, Europe, Asia and beyond are discussing. It's a fabulous tip-off service or, to use the journo-jargon, news aggregator.

I use it to draw attention to a piece I've written, or broadcast that I've done, or sometimes to comment on an issue of the moment. I'm not interested in droning on about walks on Hampstead Heath, how my beloved Chelsea are doing (not very well) or getting into manufactured spats with people. But many people are – and they are followed by more people than I am – so good luck to them.

My journalistic training came from the Reuters news agency, where we were schooled in reducing everything into a maximum of 30 words – who, what, where, when, why and, most importantly, so what? I remember fondly an exercise in which we had to summarise War And Peace to that length. Concision has great merits (one needs only to scroll down a long, turgid email to separate out those who can marshal arguments quickly and those who cannot), but what concision struggles to do is to provide context.

To strip it back to the first principles, freedom of expression is trumped by other considerations only where the context demands it. To use that time-honoured example: when anyone shouts "Fire!" in a crowded theatre. It is not because they shout "Fire!", no matter how crass that might be, but the fact that a crowded theatre could lead to a stampede. As the human rights and free speech campaigner Aryeh Neier points out, Americans base free expression on context. On the issue of race, is an offensive remark likely to incite hatred or violence? The Europeans (and increasingly the British) take a more literal view where the words themselves constitute the transgression.Remember the Robin Hood airport case? Two years ago today, a trainee accountant, Paul Chambers, sent a tweet to his 600 followers, joking about the closure of his local airport in Doncaster because of bad weather. "Robin Hood Airport is closed. You've got a week... otherwise I'm blowing the airport sky high!" The following May, he was convicted under the Communications Act 2003 of sending a menacing electronic communication. He lost his appeal.

His case attracted wide public attention, with a number of celebrities rallying to his cause, and thousands of people re-tweeting his tweet in solidarity. None of them fell foul of the law. Again, context should have been the key. Was this man really planning a terrorist act or encouraging one? A cursory investigation by the security services would have found that out.

Twitter is fun, fast and furious. It manages to be a marketing tool and a democratiser at the same time, with public figures chatting away with the public whenever they are minded, or provoked, to do so. The hullabaloo around the opening of an account by Rupert Murdoch this week and the opening of a later-to-be-discovered fake account in the name of his wife, Wendi Deng, testifies to the febrile nature of it all.

Too often, Twitter militates against the development of an argument beyond the soundbite. It creates the need for a reaction, demanding the shrill in order to be noticed, only to cut down the offender on a whim. Politicians took some time to adapt to the advent of 24-hour television news in the UK more than a decade ago. First they under-estimated its value; then they over-reacted to its power. They now have a slightly (only slightly) more balanced approach to it.

The same should surely apply to social media. Some people may enjoy getting into a tizzy hundreds of times a day. We are in danger of losing the tremendous advantage that this technology brings in our rush to instant judgement. For politicians such as Ed Miliband to react so portentously to an off-the-cuff remark suggests, yet again, that reflection loses out in modern media land. And it has taken me more than 140 characters to say so.

John Kampfner is the chief executive of Index on Censorship

twitter@johnkampfner; www.jkampfner.net