People speculate about Donald Rumsfeld’s often-quoted reference to known unknowns and unknown unknowns. According to Wikipedia, the latter term was first used in a D.H.Lawrence poem. Despite this, few people argue against the analysis – and it most certainly applies in the world of public consultation.

Let us take the current debate on the forthcoming EU referendum. Our media is awash with information and advice, yet there is a widespread view that it may serve to obscure rather than enlighten. We are literally drowning in data and many people feel that they need a Ph.D. in statistics and economics, before they can form a view as to the balance of advantage for one side or another of the argument. Might we call this information overload?

For those who plough through the competing claims and counter-claims, there may dawn the realisation that in between the cracks, there is a lot that we just do not – and maybe can not know. It is this that poses such a challenge to anyone organising public consultations.