Derek Rose, who got a four-year jail sentence yesterday for blackmailing Tamara Ecclestone, does not sound like a charming man. Rose, who dated the Formula One heiress a decade ago, more recently tried to extort money from her by suggesting that he had been offered a substantial sum by a tabloid for his story, and asking if she might be prepared to make a counter-bid. The tabloid offer was fiction, but Rose was nonetheless hoping to get £200,000. All of this is obviously the behaviour of a complete scumbag.

But should it really be a crime? All our instincts say yes, but it’s less clear-cut than it appears. Consider another example. Let’s say that Rose is, in fact, ready to sign a deal with a red-top; but instead of going to his ex and offering her the chance to come up with a better proposal, he goes ahead and spills his guts to the gutter press. He’s committed no crime. And yet the consequences for Tamara Ecclestone are probably worse. At least in the first scenario she has the chance to keep this information private if she thinks it’s worth it. This time, her privacy has been heinously breached and she just has to put up with it. To put it another way: if it’s legal to behave like a monster, how can it be illegal to ask for a payment not to?

There was a real-life example of this yesterday when the comedian Jason Manford found his “SEX TEXT SHAME” splashed across the front page of The Sun. And if you’re blinded to the legal quandary by all this celebrity grot, think about your beloved grandmother’s brooch. Someone has got the brooch by legal means, and intends to sell it. You want the chance to buy it, even if the price is extortionately high, right? It might be ethically dubious to charge you a premium, but does it really make sense for it to be a breach of the law?

In the end, there’s only one inviolable defence of the law on blackmail, and it’s inviolable mostly because it’s irrational: this act makes us shudder, and we don’t want it to become an ordinary transaction. We feel that society is made a little more shabby for all of us if no one faces censure for doing something so obviously cruel, calculating, and greedy. Logical or not, this is just about enough for me.

It raises another troubling question, though, and one I can’t quite answer. If we all agree that blackmail should be barred, why shouldn’t selling someone out to a newspaper be barred? If Tamara Ecclestone should be protected from Derek Rose, why shouldn’t Jason Manford be protected from The Sun? There may be no case for a change in the law. But anyone who nods appreciatively at the news that Rose has got his just deserts should think twice before clucking their disapproval at the behaviour of that foolish comedian.