(Image: Woods Wheatcroft)

There are clear lines between scepticism and denial, but telling them apart can be tricky in the real world, says Michael Shermer. Read more

Denialism satisfies deep emotional needs. That makes it easy to encourage and hard to counter, saysDebora MacKenzie. Read more

If the truth is inconvenient, put up a smokescreen instead. It works wonders for big business, argues Richard Littlemore. Read more

It's easy to send a lie flying around the world, and almost impossible to shoot it down, says Jim Giles. Read more

Michael Fitzpatrick argues that calling an opponent a denier is illiberal, intolerant and ineffective. Read more

We must let denialists be heard, and respond with patience, vigilance and tireless rebuttal, says Michael Shermer. Read more