If you say, “I’m never eating chocolate ever again”, that’s a rule. It’s also not a very good one. You could last a few hours, perhaps even days or weeks, but if you see your favourite chocolate on sale after a long day of work, you might give in.

Rules can be very powerful. Rules govern how society runs, how people treat one another, and even how we behave ourselves. Unnegotiable rules like drinking water every day, or to never smoke can alleviate mental space for harder problems. But the problem is, like the chocolate rule, people change. So, how can a rule be followed when the person the rule is for continuously changes?

The explanation for this shifting and paradoxical behaviour is called the empathy gap: a cognitive bias where people underestimate the influences of visceral drives on their attitudes, preferences and behaviours. This explains why one day, you detest chocolate, whereas another day you want nothing more than chocolate. Our hormones can quite literally dictate our mood.

So, how does one make lasting, effective with such shifting personalities? Professor Sendhil Mullainathan, in an interview with The Knowledge Project, suggests we treat ourselves like a democracy:

A lot of people I’ve seen pick rules willy-nilly. That’s just handing over power to the person in that moment who thought that was a good idea…you really want to protract the process of picking a rule.

Suppose you want to implement a rule, like “no dessert after meals”. That’s not a rule that’s been decided; that’s a rule that’s been proposed. Over the next week, ask every self that emerges how they feel about this rule. If by the end, every self agrees with this rule.. our confederacy of selves are all in agreement.

Well thought-out rules have the property that they are ones many parts of our selves subscribe to.

It’s not inaccurate to see ourselves as mini-democracies. How we behave when we’re rested and full is completely different to when we’re tired and hungry. This means that for the sustainability of a rule, get permission from all selves. Because all it takes to destroy a rule is one rebellious person emerging.

To set effective rules, make sure all your parts agree first.