Assumptions: What Could Possibly Go Wrong?


Your brain loves to make assumptions.  They’re efficient.  They’re practical.  They’re quick.  But often, they’re just plain wrong!

Assumptions Data
Photo: Pixabay/evertonpestana

Early on in a big IT project I’m familiar with, a tiny and seemingly inconsequential decision was made…  The project was incredibly complicated – it involved replacing one big complex IT system with another big complex IT system with no downtime and over 100,000 people dependent on seamless delivery.  There were a multitude of ways that things could go wrong.

The decision I’m referring to here was deceptively simple.  Keep as many things as possible the same between the two systems so that users don’t get confused and make mistakes.

It wasn’t written down anywhere, but it infused a significant number of smaller decisions.  Like the design of forms for data input.  The logic went “people are used to the current forms.  We’ll update the logo and a couple of cosmetic details so it’s clear they are the new forms, but otherwise, keep it the same.  Besides, our new system is so intuitive and functional that hardly anyone will need to use paper forms.”

Sounds like a good idea, right?


The original forms had been designed to support data entry in the old system.  A system that was being replaced because it was heavily reliant on service centres full of specialists supporting the users to complete the forms correctly.  The forms matched the data input fields in their system.  They weren’t designed to be logical or simple for users.

Assumptions Paperwork
Photo: Max Pixel/CC0

So when the new system was launched, this tiny and seemingly harmless assumption caused a snowball of massive proportions…

  • Users remained equally confused by the forms, but no longer had service centres full of specialists to support them to complete the forms correctly
  • The new system wasn’t intuitive, and significant high-volume functions did not work at all
  • The new forms did not bear any resemblance to the data-entry field layout in the new system, so when the forms came flooding in… and they did… the new (smaller and less experienced) service centre was completely overwhelmed entering data in an illogical order into an unfamiliar system.

Errors were rife, and delayed processing resulted in users resubmitting their paper-work, compounding the problem… The errors meant rework, and multiple service centre staff working on the same piece of work meant communication was poor and responsiveness was non-existent.

The result?  Some people lost their jobs, a lot of unanticipated money had to be spent to correct the issues and catch-up with the unprocessed requests, and the organisations in question spent a huge amount of energy and effort in crisis mode…  All because of an unchecked assumption.

OK – So How do I Avoid Making Assumptions?

You almost certainly can’t.  But that’s an assumption – so feel free to question it!

Your brain – just like mine, and almost everybody else’s – has evolved to be as efficient at helping you make decisions as possible.  We are great at spotting patterns (even when they aren’t there), we are great at spotting differences and change.  We are terrible at noticing things that are familiar and we are terrible at spotting flaws in our own logic.

Assumptions Poisonous Berries
Photo: Pixabay/JamesDeMers

These traits developed to keep us safe from predators.  To ensure we didn’t eat the poisonous berries.  To connect us with our tribe so that we could have safety in numbers.

But these same traits make us terrible at assessing actual levels of risk, make us break out in a sweat and have a physiological response equivalent to meeting a sabre-tooth tiger at the thought of speaking in public, and mean that we simplify our decisions by making assumptions without properly figuring out whether they are accurate or not.

Instead: Deliberately Question your Assumptions

Now that sounds obvious and simple.  But it is neither.

The specific purpose of assumptions is to save you time and cognitive resources – you aren’t supposed to be aware you are doing it – so how do you question them?

Step 1: Be mindful of when you are about to make a decision

Assumptions are almost always a tool for decision making – so the simple fact that you are about to make a decision needs to be apparent to you, and it needs to come into your awareness that a decision is required.  Sometimes this is obvious… there’s a memo on your desk with options to choose from, you are tossing up between two different brands of smart phone to purchase.  Sometimes it’s more subtle.  Like deciding which of your direct reports you allow to linger longer in your office and which ones you move on promptly at the end of your meeting.  Like choosing which projects you’ll give closer scrutiny to or contribute more of your own energy to.  If you struggle with this, you may find that meditation assists you to become more aware of your own thinking, and be able to notice what’s going on around you, rather than just reacting to it.  An app like Headspace can be really helpful for this.

Step 2: Pause and ask some questions

Question Mark
Photo: Unsplash/emily-morter

Questions are incredibly powerful – whether they’re out loud or in your head.  Here are some that I like to


  • What needs to be true in order for this decision to be the right decision?
  • What are all the ways this might not play out as I expect it will, and why?
  • What actions must other people take for this to be the right decision?
  • What would xxx do? And why? (insert name of someone who frequently disagrees with you)

Many of these questions can also work with a group – so be open to discussion assumptions out loud as well.

Step 3: Document your assumptions

This might sound strange, but time passes, memories fade, and things that seemed sensible and logical can look absurd and nonsensical with the benefit of hindsight.  Wherever you can, document the assumptions you made in reaching your decision, so that you can reflect on the accuracy of your identification of assumptions and improve your skills over time.


What assumptions have you made that turned out to be really wrong?  Do they seem obviously with the benefit of hindsight, but were completely invisible at the time?  I’d love to hear from you!


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