Piers just wants to belittle people and try to make them look like idiots, that's why he immediately goes for the insults as soon as he is challenged. Despite all the facts that have been relayed on his show he still argues the same points.
I am all for a debate but with some people it is futile as they don't want to change their mind. The only useful reason I can see for anyone to to even debate him is so that someone in his viewing audience that might change their minds by hearing some legitimate stats and information.
Most tv pundits are so full of themselves they just assume they are smarter than us mere peons. Most of them are so far out of touch with reality they couldn't see it with a high powered scope. These days they are concerned more with the leftist agenda than they are with common sense or facts.