The economics of decluttering: how I learned to ignore sunk costs

There must be a word for it.

The unique condition of not actually being a hoarder, but being obsessed with people who are.

Many's a night I've lost sleep staying up to watch Hoarding: Buried Alive, a TV show in which psychologists help obsessive-compulsive hoarders transform their homes from garbage tips to havens of clean surfaces, freshly exposed carpets and gleaming bathrooms.

It's time to de-clutter your wardrobe. Photo: Getty Images

I'm not a hoarder, but I've struggled for years to squeeze a lifetime of possessions into a series of 1800s workers' cottages I've rented in Sydney's inner west.

Instead of decluttering – actually reducing the volume of stuff I own – I became obsessed with finding appropriate "storage solutions". I became a VIP shopper at Howard's Storage World, sinking probably thousands of dollars on clear shoe boxes, leather magazine holders, slimline CD and DVD sleeves, shelves, racks, multi-functional coat hangers and every variety of cute box.

Instead of reducing my stuff, I added more. Constant deprivation of built-in robes will do that to a person.

But it's all changed.

Over summer, I stumbled upon the work of decluttering guru and Japanese tidying expert Marie Kondo. I devoured her 2014 bestseller The Life-Changing Magic of Tidying Up, the central thesis of which is to put everything you own on the floor and only keep the items that give you joy. There is a particular order: start with clothes, then books, papers, miscellaneous stuff and then finish with sentimental items like mementos and photos.

Constrained by a curious toddler and a suspicious husband, I did my work in secret, in small bursts and not quite in the correct order.

But over the course of a few weeks, I marched more than 20 garbage bags of stuff to our bins. Yes, everything went to landfill, rather than recycling. There were a few reasons for this. First, I have a habit of collecting things for donation, only to have them hang around the house for so long, I end up unpacking them. I also know we live in an age of cheap, disposable goods, meaning nobody wants or needs to buy my year-old trainers. Finally, I wanted to raise the cost of accumulating stuff. I now know that anything I buy and don't use will end up in landfill and that makes me feel bad and less likely to buy it.

The thrill of chucking stuff out was immediate and visceral. First, two bags of old musty manchester. Two more bags of uncomfortable shoes, never-used handbags and scarves. Five or so bags of ill-fitting and outdated clothes. Two bags of obsolete technology, including floppy disks and my first laptop. Then bags full of paper: old reports, newspaper clippings, postcards, pamphlets from old holidays and a Sydney UBD. Remember those?

The year 12 formal dress my mum helped me make. A spare wedding dress I bought before I found another one I liked better. Old school uniforms scribbled with barely legible farewell messages. A pebble in the shape of a love heart discovered on a beach with my first boyfriend. A set of watercolour paints. Knitting needles. Old pieces of fabric. Free cosmetic samples.

Out. Out. Out. Damned clutter.

But progress has slowed since I've come to the more sentimental items: letters, cards, diaries and photos. Despite several attempts, I can't bring myself to throw them out. Worse, the process of looking at them has submerged me in a wave of nostalgia that has made me question earlier decisions.

I wonder, should I have kept that pebble? That dress? They're in the bin now, in God knows which dump. I'll never touch them, or see them again.

Have I let too much go?

According to the Kondo theory, the process of discarding things, done properly and methodically (which is far from the way I've done it) should leave one feeling relieved and rejuvenated. Her book is full of stories of clients who have lost weight, found new jobs and excelled in their life since their purge.

And I'm definitely enjoying some benefits. It's far easier to get ready in the morning without rifling through an overstuffed wardrobe of clothes I don't really like. I have almost empty shelves in the bathroom where it's easier to access my most used items.

I've pretty much quit shopping. I know exactly what I own already and I know the stakes are high if I make a careless purchase.

I no longer stalk the house wondering what I can chuck out. If anything, I wander the house alert to the ghosts of objects farewelled.

But, as usual, I take comfort from economic theory. One of the main pieces of advice economists offer is to ignore "sunk costs". Money we have spent in the past should not influence future decision making. Just because you paid $15 for that burger and chips doesn't mean you must finish every one. Just because you spent $350 on that dress doesn't mean you should keep it if you will never wear it again and it bothers you that you have no room to store it.

Decluttering is basically a huge exercise in ignoring sunk costs. And only when you have learnt to do that, can you begin to make better decisions in the future.

Economists also advise to make decisions "at the margin". In other words, in the here and now. Ignore everything that has transpired: you should only do something if the marginal benefits will exceed the marginal costs. Never act out of regret, fear or guilt. Think always and only of your future happiness. What will make you happy now and tomorrow?

As it turns out, letting go of the past is not easy. It can open an uncomfortable void: if that object I thought was important is not, then what is? That empty space is liberating and terrifying at the same time.

But the process of discarding has taught me that the things that bring me true joy are not things, but people. They're not memories of the past, but ideas about what the future could bring.

Could it be that nagging feeling of emptiness is not a void but a vessel, waiting to be filled with new adventures?

It is by learning to ignore sunk costs that we attune ourselves to future happiness. And that is worth a little discomfort.

Twitter: @Jess_Irvine