It was the American moral philosopher Judith Jarvis Thomson who first introduced me to the concept of thought experiments. Thomson would take real life moral dilemmas and transplant them, via some far-fetched analogy, into absurd alternate realities, wherein the reader could engage with the essence of the original question, freed from the straitjackets of politics or personal prejudice.

 Most famously, in 1971, Thomson made a case for legalised abortion by concocting a story in which readers were invited to imagine they’d been kidnapped and awoke connected, via intravenous drip, to the body of an ailing violinist who, they were told, would need a continual supply of the reader’s blood for the next nine months, if he was to have a chance of surviving.

As a younger man, this approach to thinking really fired my imagination. I would compose thought experiments all the time. Here’s one I came up with while arguing about East Germany with a girl I’d just met in a bar. I was insisting that life under the Honecker regime had been hellish and oppressive. She disagreed, saying things really weren’t all that bad.

 It turned out this woman was born and raised in the GDR and had some fond memories of the place. Whereas my own expertise derived largely from having seen the film The Lives of Others earlier that evening. In the circumstances, I felt a game-changer was required...

Once upon a time - I told her - there was a prosperous kingdom ruled over by a benevolent king and queen. One morning, the king and queen were trampled to death by a herd of stampeding rhinos and the throne passed to their son, a pampered little prince. Without his parents around to offer love and guidance, this spoiled brat soon became a fully-fledged tyrant.

The new king had a wooden leg and, after a misunderstanding at the grand opening of a cash  and carry, he became convinced his subjects mocked him for this behind his back. So next day, he issued a terrible edict. Every man, woman and child in the kingdom was to have their left leg amputated just like him.

His soldiers went to work, hacking the left legs off every citizen in the land, before turning their swords on themselves. The streets and rivers soon ran red with blood. Cries of despair could be heard in every hamlet. Over time, the new king mellowed and became, in some ways, an enlightened ruler. But on this one issue he refused to budge.

Decades passed. By the time you and I were born, the king was an old man and foot amputation was a painless childhood rite of passage. On the day of our procedure, each of us was given cards and gifts, and lavished with attention.

A skilled caste of craftsmen had come into existence, producing beautiful and ornate wooden legs, illustrated with portraits of dashing matinee idols and idealized depictions of rural life. Indeed these craftsmen’s workshops often became focal points for local communities; somewhere growing teenagers would go to have new limbs fitted or sometimes just to shoot the breeze.

Maybe your parents first clapped eyes on each other in one of these places. Maybe your mother carved your father's initials on her new prosthetic and keeps it as a sentimental treasure to this day. Meanwhile, at the Paralympics, the kingdom's athletes brought home gold after gold after gold.

Oh, yes. That’s something else I should have mentioned about thought experiments. They don’t have punch lines. They rarely even have endings. They just peter out, like small talk in an elevator. The point I was making there was rather a banal one: that a person can grow accustomed to just about anything. We were talking about East Germany. But looking back, I wonder if I wasn’t really talking about grief.

At the time, I’d suffered four major bereavements in five years. This wasn’t something I mentioned much in bars. It wasn’t even something I dwelt upon in private. A and B were two beautiful sisters killed in a horrific accident overseas a few days after my 21st birthday. (A third girl I knew less well also lost her life in the same incident.) The first locals to stumble upon the girls’ bodies stole their wallets and their belongings. So they lay in a ditch five days before the alarm was raised.

I was a pallbearer for A and slept in B’s bed the night of their funeral. At the graveside, their mother lurched forward wanting to say something. In her anguish, I couldn’t immediately grasp what was the matter. She wanted to know which coffin was which. She wanted to know which one of her daughters we were putting in the ground.

When the prayers were over, C tugged at my arm and offered quiet condolences. Considering the state of her health, I was surprised she’d made it to the church, let alone to the cold and windswept graveyard. She hadn’t known A or B personally, insofar as I’m aware. She was there to support me and I appreciated it.

A couple of years later, I kept a late night vigil at C’s bedside. She was breathing through a ventilator, a shrivelled, grotesque parody of the woman I had loved. At 4am, almost imperceptibly, her grip on my hand relaxed. I summoned the nurse and asked her if the breathing noise I was hearing came from the patient or the machine. “It’s from the machine,” the nurse confirmed. In that case, I said, she’s gone.

Later that same day, D showed me how to prepare for a wake. We stopped all the clocks, covered over the mirrors and established a line of credit at the nearest off-licence. Two years later, I found myself repeating the process for him. He had keeled over after playing a game of indoor soccer.

At the time, these were just a scattershot of unrelated, tragic events. It never felt like a single narrative, let alone one in which I played the leading role. In each case, others had far greater claims on grief than me.  

I was concerned for their welfare and never for my own. This wasn’t gallantry. It’s just easier to mask your own feelings sometimes than it is to confront them. As I understood it then, this just came with the job description for being a man. Which isn’t to say I managed to block it all out. For a long time, I was secretly haunted by visions of A and B’s final moments, by the sheer terror they must have experienced when they knew they were going to die. A couple of months after the accident, I was having trouble sleeping at night. D and I were in a cafe on a Saturday morning when the owner approached our table. When you’re 21, adults still tend to look through you and behave as though you aren’t there. So I was surprised to find it was myself, and not D, that the cafe owner wished to have a word with.

“Those two girls, your friends,” he barked. “They’re buried out at the cemetery in Aghamore, aren’t they?” I nodded. “Have you been out there lately?” I gulped. “I mean at the graveyard, since the funeral?” he continued. “In the past week or so?” What the fuck business is that of yours?, I should have responded. Instead, I stammered. Yes, I was there yesterday. 

A planning notice had just appeared in the local newspaper, announcing a new property development on the old graveyard road. “You must have walked past the site,” he implored. “Did you get a look at it at all?” He was fishing for gossip. He had question about units and frontage and builders vans. None of which I was able to answer to his satisfaction. It was surreal, like an out of body experience. I felt like begging him to stop. But he didn’t. And D just sat there, fucking oblivious, sipping coffee and reading the paper.

 I drank a lot in those days. I did a lot of drugs and got in a lot of fights. All of this seemed normal at the time. But looking back, I can’t help wondering if I was acting out?

 For a lapsed Catholic – which I most certainly am (after all, there can be few greater stress tests of one’s disbelief than to close the lid on a person you love desperately and accept you’ll probably never see that person again) – this line of thinking is very seductive. The idea that I could make a Devil out of grief, and absolve myself of responsibility for all of the stupid things I’ve done since then has some obvious attractions. But that’s self-serving bullshit. I’m pretty sure I’d have done all those things anyway.

 It was after D died that I walked closest to the ledge. I would behave like a normal person at home, at work, and in the pub afterwards with my friends. But when I was walking home, after a few drinks, I would torture myself replaying painful scenes and conversations, over and over, in my head. In the darkness and the anonymity of the city, I finally allowed myself to cry.

 I became acutely aware of the winos, beggars, junkies and prostitutes wandering like ghosts in our midst. I fancied now I felt a little of what they felt. One night, when I was walking down Fitzgibbon Street alone, an ambulance peeled past and mounted the kerb ahead of me. Paramedics jumped out. For a moment, I thought that they had come to take me away. And I was willing to go with them. But they brushed past me, up the stairwell into the flats.

 There’s no happy ending in all of this. Not really. But time does have a habit of passing. Things move on. Stuff happens. New memories are created. If you’re lucky, those are happy memories, memories you wouldn’t swap for the world, even if some people were no longer around to have been there. In some cases, things happen for the better that could never have happened if the deceased was still alive. This is the accommodation we come to with loss. This is the only accommodation we can come to with loss.

 The day after the Berkley tragedy this summer, I visited A and B’s grave for the first time in several years. There were a couple of kids’ bicycles slung against a wall by the cemetery gates. My friends were buried with their grandparents, in the old section of the graveyard. A lot of the old tombstones there are falling down now and many of the graves are overgrown.

 At the top of the hill, I paused at their grave. I wondered, if the girls had survived, would we even still be friends? Would we have fallen out with each other, or grown apart? Would we be Facebook friends, who liked each other’s photos once in  a while, but hadn’t spoken in years? I hope not. But you really just don’t know.

Then I turned around to admire the rolling green fields and crumbling stone walls that spread out for miles in every direction. They sun was shining. It was a beautiful day. Two small boys were cavorting in the ruins of the lovely old chapel, overlooking the girls’ family plot.  With a friendly greeting, I tried to convey that it was okay for them to be there. I really didn’t mind. But the two boys scattered in fright. I could hear them in the next field, still shrieking and laughing as they ran.

 This is the natural order of things, I said to myself. Edifices crumble. Grass grows over the stones and, eventually, children come to play on that grass. And there is beauty in that to be sure. But it would be better if some stones were still standing. It would be better if I still had two legs.