Let's say you are in a meeting. You want to persuade your colleagues to see the benefits of adopting a shared digital calendar.
Your presentation seems to be going well until Fred leans back on his chair and announces, 'It's not worth the hassle. My diary works well for me. I'm not changing.'
We're indebted to many researchers and thousands of salespeople for this one. It's been extensively field-tested.
It can be used in dodgy, manipulative ways, but you can use it honourably. The ethics depend on the context, so I'll have to leave the ethical issues to you to mull over.
It's the consistency principle, known to salespeople as the 'foot-in-the door technique'.
Here's how it works.