20% of the public are on Twitter in the UK and US, about 20%. Of the 20%, 80% of the noise is made by 10% of the 20%. And it tends to skew to the extremities of the debate on right and left. You can create an impression of all this stuff being sort of sanctioned by the majority. It of course is not. So why Twitter gets everything wrong? Piers says he has a real problem with people who can't argue with that.