Thinking Tools #3 – An upside down way to find gaps in our thinking

Thinking Tools #3 – An upside down way to find gaps in our thinking

The first time I recall using the inversion strategy was during my interview with McKinsey.

I remember a Senior Engagement Manager called Saimond putting me through my paces around a case and then posing a leading observation.

“So, you have given me some great demand side ideas there …”

As someone with a kindergarten teaching and then communication background I had not used economic concepts much. But thankfully I had helped review my university boyfriend's economics essays and twigged that he wanted more and different ideas from me.

So, I responded that he was right, and that perhaps he would like some supply side ideas too?

I then invented some on the spot. Using opposites has turned out to be a useful thinking strategy in many situations since.

It is also another model discussed in Shane Parrish's new book The Great Mental Models which I posted about last week.

Given some of you have asked me to pick my way through Shane's models in bite-sized stages, I am extending my series of posts on this book. Today's focus is on opposites, or as Shane Parrish calls them ‘inversions'.

There are a number of natural places to use this strategy.

Firstly, when choosing a set of options to evaluate. He offers two strategies to help you use inversions:

  1. Start by assuming that what you are trying to prove is either true or false, then show what else would have to be true
  2. Instead of aiming directly for your goal, think deeply about what you want to avoid and then see what options are left over

Secondly, when ensuring our ideas are MECE. This works both when we are communicating and also when solving problems (which I will talk more about during the Hypothesis-driven Problem Solving series I am planning for March).

I thought you may find it useful to have a list of examples of where I have used inversions recently that you could also apply in your own communication. 

I have ordered them according to the three lenses we use for checking whether our ideas are ordered well:


  • Internal versus external (eg as in forces acting on something)
  • Supply versus demand (eg economics)
  • Hard versus soft perspectives (eg McKinsey 7S framework)


  • Current versus past or future (eg activities, plans)
  • Experienced versus inexperienced (eg team members)
  • Old versus young / new (eg equipment, technology)


  • Hot versus cold (eg could be literal or metaphorical)
  • Increasing versus decreasing (eg prices)
  • Large versus small (eg anything measurable!)

Remember: step one when organising your ideas from the bottom up is to work out the categories. Step two is to work out what you are saying about those categories.

I hope that helps.

Talk soon,


PS – Related posts include:

From this series …
  1. 5 Ways to be MECE in your communication
  2. Further thinking tools

Past posts on thinking skills …
  1. How to use your critical thinking abilities to turbo charge your communication
  2. Strengthen your critical thinking abilities
  3. 4 Ideas to make structured thinking stick
  4. Awesome problem solving strategies
  5. The value of thinking-top down versus bottom-up (for Sprint and Momentum Members)

PPS – I receive a small commission if you click the link and decide to purchase a copy of Shane's book from Amazon.


Davina has helped smart people all over the world clarify and communicate complex ideas for 20+ years.

She began this work when she joined McKinsey & Company as a communication specialist in Hong Kong where she helped others use the Minto Pyramid Principle. She continued helping others when living in New York, Tokyo and now back in Australia.

Her clients include mid to upper level experts across many disciplines across Australia, Asia Pacific, New Zealand, the UK and the US.