Inversion is a powerful mental model that tries to understand the world and make improvements by avoiding the undesirable rather than to focus on merely the desirable.
In order to be happy, we could eliminate that which makes us unhappy.
To improve decision making within an organization, it is easier to avoid stupidity than to seek brilliance.
To encourage a particular behaviour, we could focus on removing the obstacles to make the intended behaviour easier.
When we encounter a problem, rather than merely counter it head on we could explore how to attack it from the flank.