I am Mr Rational.

Strict atheist, anti-tribalist, and demander of evidence, statistics, margins of error. Black cats, broken mirrors and ladders hold no fear for me.

In fact, the quickest way you can put me off you is to ask what star sign I am.

Which is why it is so strange that 5 years ago, when my eldest was up for his measles, mumps and rubella (MMR) vaccination, I had a genuine wobble. Should I? You know, with all the fuss that there’s been in the papers (and papers I don’t even read)? Should I risk it with my own flesh and blood?

Fortunately Mrs Rational put me straight or I too might be panicking like all those parents in Wales who demurred and ended up putting their children at risk of dangerous disease outbreaks.

It struck me recently that there were great parallels between the MMR scare and the climate change ‘debate’. In both cases, a small number of people have managed to seed doubt in people’s minds using circumstantial anecdotes which flies in the face of robust scientific evidence. But that doubt is very powerful. Do health professionals really know what they’re doing? How can the world be warming if it’s snowing?

It is tempting (and hands up, I’ve succumbed) to fight such irrationality with a deluge facts, graphs and hard evidence, but it rarely works. In the elephant/rider/path model of human behaviour, the elephant/subconscious is always more powerful than the rider/conscious. If the elephant is spooked, there’s precious little the rider can do to calm it down.

So, what’s the answer?

My Green Jujitsu approach says acknowledge the power of the irrational mind and try to use it to your advantage. Inspire people to do the right thing by making it inviting, fun and in line with our cultural norms.

Unfortunately the merchants of doubt will always be there, but lets worry about what we can change, not what we can’t.