Last week Liverpool Mayor Joe Anderson announced plans to offer a one-year exemption from council tax to anyone who provides evidence of others who fail to clear up their dog’s poo.

I hate dog doo as much as the next person, but this stance really riled me. Our political institutions and the people who lead them ought to be better than this. Here are two reasons why Mayor Anderson should reconsider his stance

1. We need to build trust, not pit people against each other

A policy that directly encourages people to benefit from others’ ill is likely to erode, not build trust.

The Government’s most recent Community Life Survey shows a steady decrease in people who feel they strongly belong to a community. A similar trend plays out for people who say they chat to their neighbours at least once a month. These numbers, against a backdrop of what we hear is a divided Britain, may not be so surprising.

What is surprising though is to see a policy like this being developed in light of this context.

At a time when feelings of cohesion are faltering, we ought to be building trust between people, not introducing policies that erode neighbourliness.

Don’t get me wrong. I’m wholeheartedly in favour of people stepping forward to right wrongs. Using social norms can also be an incredibly powerful motivator to change behaviour. Numerous schemes, from reducing drink driving to tackling discrimination, have demonstrated the power of persuasion, tapping into people's innate need to feel part of society.

In this case though, shaping social norms is not the lever being used to influence behaviour. Instead we see financial incentives provided to the general public to spy on others. In one foul swoop the social contract between people is being undermined, and trust is eroded. In fact Anderson himself has already started along an ‘us’ and ‘them’ path saying: “These people are not your neighbours, they are environmental criminals.”

2. Evidence should still trump opinion.

The second reason this policy caught my attention is that it doesn’t appear to be based on evidence of what works.

In fact, the proposed intervention might well do harm, even exacerbate the problem. There is evidence that material rewards can "crowd out" intrinsic motivation to perform particular tasks. In other words, the council tax waiver could deter people who might have otherwise volunteered to litter pick, or step in to ask a dog fouler to do better. Rather than encouraging more people to step up and do the right thing – engage in social action – it could lead to a situation where people expect economic returns for helping to improve their community.

All is not lost though.

Mayor Anderson would do well to consider the evidence.

Thanks to the efforts of Keep Britain Tidy and others like them, we are developing a better understanding of what works in reducing dog fouling. This news should be welcome, given a 2011 meta-analysis found no good quality studies that have looked at the effectiveness of dog fouling interventions.

Shaping behaviour rarely involves one solution. A mix of push and pull is needed to deliver the desired results and this is where the interplay of different interventions comes in. Making it easy for people to dispose of waste, communicating the health implications of dog fouling, developing social norms that littering is not acceptable, and using legislation (including fines) as a last deterrence all have parts to play.

Liverpool City Council knows this already – its Active City Strategy for example identifies the need to employ a range of different measures to help increase people’s fitness and wellbeing. What’s missing perhaps is applying this thinking to the less glamourous area of dog poo.

The 2010 ‘There’s no such thing as the dog poo fairy’ led to decreases of up to 90 per cent in dog fouling for example. This campaign drew directly on people’s sense of wanting to do the right thing, as opposed to assuming they are somehow born criminals (as Joe Anderson might have us believe).

Other work by Keep Britain Tidy found posters with eyes watching placed near sites where dog fouling was common to be effective. Four different posters were trialled, each with a pair of eyes and the message “Thoughtless dog owners: We’re watching you.” Three variations on this message were trialled along with this version. While all versions of the poster were effective, the most impactful one was the one with a positive reinforcement message “9 out of 10 owners clean up after their dog, are you one who doesn’t?”

There are many other innovative ideas that may be worthwhile exploring, many that draw on more positive aspects of the human condition.

So, come on Mayor Anderson. Be the Mayor Liverpool needs! Be the Mayor who favours community, evidence and better outcomes at lower cost. Your city is one built on sport and pop anthems the likes of You’ll never walk alone, Come Together and We can work it out. You don’t really need such a big divisive stick to address this issue. Imagine what a change of policy, and a change of heart might do.