Often, if you’ve made an assumption about something, and you haven’t spotted that it’s an assumption, it has a butterfly effect. Six months later you realise that because of this assumption the project you’re working on is moribund and nobody is prepared to throw out all the work and go back to the drawing board. So it goes.
The most dangerous thing about an assumption is when one person releases it into the air, another person inhales it deep into their thinking, agrees with it and takes it onboard as fact. Then they carry it around with no symptoms to speak of. And before you know it, it’s endemic. Everyone believes it to be true because nobody knows where it came from and everyone shares it. And then it’s terminal.
It usually takes someone to question or challenge an assumption to defuse the coaction effect. It’s only when an assumption is called out and challenged that it can be addressed and contained, quarantined and eradicated.