Over the summer I spent some time in Scotland. At the end of our stay in Edinburgh, my companion and I wanted to leave our bags somewhere for half a day, as our train to the Highlands didn’t leave until later that afternoon. The most obvious solution was the left luggage office at Edinburgh station.

Contrary to my romanticised expectations, this was not a cosy room where leather suitcases with exotic labels were piled high, but a much leaner and meaner operation, in which people’s bags were heaved up to the counter, x-rayed, and then mysteriously stowed away by the staff. As the notice on the wall informed us, leaving one’s luggage also entailed answering certain questions. I told the unsmiling employee that yes, I had packed my suitcase myself, and that I hadn’t left it unattended, but when it came to "Are you carrying any firearms?" I couldn’t contain myself any longer. I decided to answer this question with another: "Do I look as if I’m carrying a firearm?"

With my flippant response I wanted to make the point that it was stupid to ask questions to which anyone with malevolent intentions could simply give a false answer. And no one would look at me and see the next Bonnie Parker, so you could say that I was just stating the obvious. But the man behind the desk now looked even more unfriendly than before. "You could get arrested for saying that, you know," he said, with genuine menace. I could see that his words were no joke. And he repeated the original question. Of course, this time I answered "no".

It was lucky that I wasn’t in one of my more sarcastic moods, when I would probably have told him about the several mysteriously ticking packages that a complete stranger had asked me to look after, and that I was at a station (covered by the National Rail Security programme, rather than the more stringent Aviation and Maritime Security Act 1990), not an airport. However, Paul Chambers, the so-called "Twitter Bomber", was not so fortunate, when during the heavy snowfall last January he tweeted "Crap! Robin Hood airport is closed. You've got a week to get your shit together, otherwise I'm blowing the airport sky high!"

Mr Chambers is unlikely to win any awards for eloquence, but no matter. As has been widely publicised, he was subsequently convicted of sending a menacing message, a verdict that failed to be overturned on appeal this month. A similar case has also been reported lately, that of the Conservative councillor Gareth Compton who suggested, again via Twitter, that Yasmin Alibhai-Brown should be stoned to death, adding "I won’t tell Amnesty if you don’t. It would be a blessing, really." Ms Alibhai-Brown was ready to go to the police, but it turned out that someone else already had.

Now, I accept that this second instance may be slightly different. It was aimed by an elected politician at a particular individual, possibly with overtones of racism, although the reference to stoning was a specific response to the view expressed by the journalist that politicians do not have the moral right to comment on human rights abuses, such as executions, abroad. Ms Alibhai-Brown apparently receives regular death threats; her upset and concern are – perhaps – understandable. But what I find intriguing, and worrying, is that the person who reported the tweet, and the police who arrested Mr Compton, took his words to mean "I am going to see that Yasmin Alibhai-Brown is stoned to death."

What happened touches on a number of questions: whether a victim’s perception that words or actions are offensive means that they are objectively so, and whom to blame when what someone says incites, or is seen as likely to incite, others to violence. But what unites my narrow avoidance of trouble in Edinburgh, and these two ill-fated tweets, is a failure to see that these flippant words were not intended to be taken literally. It’s true that I personally was thoughtless – in other circumstances a statement of that kind could pose a real threat. I don’t want to belittle genuine counter-terrorism measures here. But my failure to give a straight "no" did not signify that I meant "yes". Terrorists and murderers, moreover, do not tend to post their intentions, phrased with a certain heavy-handed humour, on public social networking sites. As the Guardian's Charlie Brooker points out, context is key.

The OED defines irony as "a figure of speech in which the intended meaning is the opposite of that expressed by the words used; usually taking the form of sarcasm or ridicule." Other definitions stress that what matters is not that words and meaning should be exactly opposed, but that they should not be identical. Irony has been around for a long time: the term originates in ancient Greek and as a rhetorical device is discussed by the Latin authors Cicero and Quintilian. But the cases I have discussed suggest that this way of talking is no longer permissible, at least in public discourse.

What is wrong with this? Irony, if done well, may be amusing, but although calling someone "literal-minded" is usually an insult, it doesn’t refer to a serious fault. Voltaire said that "one great use of words is to hide our thoughts", but in everyday life it is often useful if you can convey to others what you are thinking, and vice versa. Obliqueness is arguably an obstacle to successful communication, an affectation best abandoned along with calling a phone a ’phone and distinguishing between envy and jealousy.

I suggest, however, that something is amiss. This is not because irony is an absolute good in itself: the problem is in the underlying attitudes here. To believe that all statements must mean exactly what they appear to mean is analogous to assuming that every action has a direct, obvious outcome. This affords no room for the possibility that some effects follow belatedly, or circuitously, from their causes, or for the potential that readers, listeners, recipients have of interpreting what is offered them and of putting it to their own use. Words cannot conceal anything, as that is not how we use them.

I’m not sure how this attitude originated. It’s tempting to blame Britain’s links with a certain nation across the Atlantic not known for its appreciation of ironic humour, but that would be a cheap shot. Moreover, America knows about funding its universities. If recent events are anything to go by, Britain is very soon going to forget how to.

The most prominent, and media-friendly, resistance to Lord Browne’s proposals has so far been directed at the vastly increased fees that future undergraduates would have to pay. But there is more to it that than. As Stefan Collini in the latest LRB has so pithily shown, the report endorses the virtual withdrawal of the grant universities currently receive for teaching, and advises instead that British higher education should become a free market. Student choice will determine most of the courses offered, and those subjects to be protected from the vagaries of student demands will be those which are of direct use to society: the sciences, technology and business.

No one would contest the idea that these disciplines are essential, and deserve a prominent place in our education system; nor are those who practise them blinkered (far from it). But the report displays an appalling literal-mindedness in assuming that only subjects that produce concrete, quantifiable results do any good in society. Lord Browne has ignored the fact that the humanities make money too. More profoundly, his report fails to acknowledge that arts subjects may be indirectly beneficial. They help explain why society is the way it is, enable people to become better citizens (or help others to do so), and offer access to a cultural world that enriches lives.

For that matter, studying subjects that aren’t of immediately obvious relevance, and being forced to make imaginative leaps to understand what other people have said or thought – to do an arts degree, in short – is an excellent way of becoming aware that not everything must have a direct purpose, and that a simple idea may harbour multiple complications and consequences. I don’t mean that we should return to the days when public policy was determined almost exclusively by Oxbridge classicists and historians. But while no single perspective should prevail in political decision-making, that is not a reason to reject more traditional attitudes entirely. I’d like to think that if the Browne report had adopted a more balanced approach, it might have reached different conclusions. It is instead indicative of a dreary, narrowly utilitarian way of looking at life. Assuming, of course, that we are to take it literally.