So, when it came to the Queasy Belfast Handshake, who felt the sicker – former IRA commander Martin McGuinness, or the Queen? They both managed convincing smiles for the camera, McGuinness's if anything the more tentative, just as his handshake appeared the more limp (allowing it to be taken rather than taking, acceding to a grip rather than initiating one), but then the Queen has smilingly shaken more hands – with what degree of indifference or insincerity or even loathing we will never know for sure – than McGuinness has.

Which, you could say, makes her the more practised politician. She slips on those white gloves every morning, as she has slipped them on for 60 years, knowing she must put her hand in some terrible places. And McGuinness's own hand, don't forget, might have been the one that signed the order to blow Mountbatten to smithereens, though McGuinness insists he had left the IRA years before that event. Something else we will never know for sure.

Grievance for grievance, the Queen had more reason to show reluctance. If not the blood of her family, then the blood of many of her subjects (if that word isn't as a red rag to a bull) is on McGuinness's hands. Were he to say the same of her, as any number of angry Republicans have been saying for him, it would be more in a manner of speaking. The Queen might be the symbol of all that Irish Republicans hate, but a symbol is, by its very nature, at several removes from the action and the sanctioning of action. That we know of, no one has died at the Queen's personal say-so. These differences, I think, matter.

Handshakes, of course, exist to dissolve precisely such differences – who started it, who finished it, etc – the grosser and the finer points of dissension no longer counting. "Shake, and let's hear no more about it," our parents and teachers used to say, as though, on the mere extension of a hand, the mind of a child – that repository of the most exquisite sense of fairness – could rid itself of all consciousness of injustice.

I never did like shaking hands after a fight. Where I knew myself to be in the wrong, I felt shamefaced about allowing someone else to accept half the blame, and where I knew myself to be in the right – which was most of the time – I hated accepting half the blame myself. It felt like cowardice. A failure of nerve and principle. Hadn't I been brought up to fight for what I believed? "Stand up for yourself," my father exhorted me, afraid I was not made of stern enough stuff, so when he was the one saying "Shake – and let's hear no more about it", I felt he was betraying his own principles as well as mine.

I gathered that time was more the issue than scruple. I couldn't go on fighting for ever with the clown who thought it a lark to pour ink into my satchel. There were other things I needed to be doing with my life. The handshake didn't pretend to be a fair resolution of outstanding differences, merely a liberation from a conflict that would otherwise consume all my time. And read this way you can see why it's so hard to get fanatics ever to shake on anything. They don't want to be liberated from a conflict that takes away their life. The conflict is their life.

Joseph Conrad's The Duel – the story on which Ridley Scott based his film The Duellists – tells of two officers in Napoleon's army who, "through those years of universal carnage", pursue a ferocious and unremitting private contest "like insane artists trying to gild refined gold or paint the lily". Here was the proof to me, when I read it, that making peace when you felt you were in the right was dishonourable, that one could go on fighting an opponent for ever, and that the desire to do so, what is more, had about it something of the pure, obsessive dedication of art.

Insane such a pursuit of pure artistry – in this case the pure artistry of the duel – might be, but what if it is only through a fastidious implacability that we ever soar above the mean accommodations that make our lives squalid.

How many handshakes do we look back on with bitter regret, wishing we had stood our ground and refused the quasi-treacherous finger-touch of peace from someone we detested? At the heart of my own distaste for rapprochements is a sneaking fear that there's perverse pleasure to be found in them, akin to the pleasure of betrayal.

I have shaken hands with sworn enemies when very drunk, knowing I will hate myself in the morning, but unable at the time to resist the sinister allure of kissing incorruptibility goodnight and going over to the other side. Ah, the sick sensuality of loving one's enemies. How smart of Shakespeare, who knew all there was to know about sinister allure, to stage Antony's temporary reconciliation with Octavius Caesar aboard a galley, where nothing stays still, where, as the liquor freely flows, every principle lurches and sways. "O Antony," declares the pissed Octavius, "you have my father's house – But, what? we are friends."

That scoundrel Yasser Arafat managed, with a smile, to imply something similar on the occasion of his famous handshake with Yitzhak Rabin, under the relativising gaze of Bill Clinton. Less of a sailor, Rabin looked as though he wanted to be sick. I admired his distaste. But, yes, all right, despite myself I admired his swallowing it just as much.

Life's a dirty business. And because we can't go on fighting for ever to make it cleaner, we have, against the rising of our gorges, to accept that our enemy sees it that way, too. With all settling of differences it's possible to feel two things at once – disgusted and relieved. No, relieved and disgusted.