Suspended Judgement

On pizza cutters and Tim Harford’s ‘Adapt’…

Pizza cutters fill me with dread.

Not because they are sharp enough to slice through crispy thin-crust pizza even though they are usually just made of plastic, which, admittedly, I do find a bit weird. No, I’m fearful of them because it struck me a few years ago that they only have a single failure mode, and that failure mode is catastrophic.

The weakest point of a pizza cutter is the hub of the wheel. It’s not particularly strong and will weaken with repeated pressure under normal use. When the hub breaks, it will almost certainly do so because the person using it is applying downward pressure in the course of dividing a freshly cooked pizza into slices. The blade will go one of two ways depending on how the hub breaks. Either the blade will leap away from the person’s knuckles, which are now plunging towards the pizza, or it will twist towards them. In the former case the person’s hand will most likely punch the white-hot molten surface of the pizza, causing severe burns. In the latter case the person’s hand may be briefly deflected from its natural course by a sharp plastic blade, causing lacerations followed immediately by severe burns.

In other words, when a pizza cutter fails, it is highly likely that it will do so in the worst possible way for the person using it.

(And therefore is a bloody liability in my book!)

Of course, the pizza cutter is not alone in this regard, there are many things that are similarly fault intolerant although usually those things are too complex for that fault intolerance to be easily visible in advance of catastrophe. Nonetheless, the metaphor of the pizza cutter has served me pretty well over the years when I’ve wanted to express my concerns about something that, were it to fail, is likely to fail so catastrophically that people tend not to contemplate it failing at all.

Anyway, I was reminded of this having spent much of the last few days reading about failure in the form of Tim Harford’s excellent new book “Adapt: Why Success Always Starts with Failure”. Harford’s core arguments revolve around how evolutionary processes of variation and selection, in constant feedback with each other, produce superior outcomes to human-devised processes that are characterised by the desire to prevent failure and minimise risk. He goes to great lengths to show how failure-friendly policies might be fruitfully applied to areas such as economic development, corporate governance, financial regulation, and several others.

It’s a good read, full of interesting stories, characters and ideas. And it furthermore contains some insights that have a direct bearing on my fear of pizza cutters:

Firstly, drawing on the research of accident-analyst James Reason, he identifies the pizza cutter’s apparent catastrophilia as the result of a so-called ‘latent error’ - an error that is already inherent in the system but that is lurking “unnoticed until the worst possible moment”.

Ultimately, however, the advice he offers for dealing with latent errors when they are uncovered is bittersweet…:

“The instinctive answer is to eliminate the errors. This is an impossible dream. The alternative is to try to simplify and to decouple these high-risk systems as much as is feasible, to encourage whistle-blowers to identify latent errors waiting to strike, and - sadly - to stand prepared for the worst.”

Well, this is me blowing the whistle on pizza cutters. Don’t say I didn’t warn you! Prepare for the worst…

Alternatively, can someone please design a pizza cutter with a proper knuckle guard..?!