Richard Dawkins has issued a half apology after claiming it would be "immoral" to carry on with a pregnancy if the mother knew the foetus had Down Syndrome.
Dawkins accepted he had used poor "phraseology" in his comments, but defiantly added "half the problem lies in a wanton eagerness to misunderstand."
The controversial British author's latest Twitter row erupted after he responded to another site user who said they would be faced with "a real ethical dilemma" if they became pregnant with a Down Syndrome baby.
Professor Dawkins tweeted: "Abort it and try again. It would be immoral to bring it into the world if you have the choice."
He faced a furious backlash for his comment, with one mother, who has a child with the genetic condition, saying: "I would fight til my last breath for the life of my son. No dilemma."
Now, in a fuller explanation on his website - entitled Abortion & Down Syndrome: Apology for Letting Slip the Dogs of Twitterwar - the author tried to set the record straight and said accusations of "Nazism, vile, monstrous fascistic callousness" and "fireballs of hatred" had been hurled his way.
He wrote: "To conclude, what I was saying simply follows logically from the ordinary pro-choice stance that most us, I presume, espouse. My phraseology may have been tactlessly vulnerable to misunderstanding, but I can't help feeling that at least half the problem lies in a wanton eagerness to misunderstand."
"If your morality is based, as mine is, on a desire to increase the sum of happiness and reduce suffering, the decision to deliberately give birth to a Down baby, when you have the choice to abort it early in the pregnancy, might actually be immoral from the point of view of the child's own welfare," he added.
Prof Dawkins claimed he had hoped that his million-plus followers would not see his comments, instead it would only be sent out to the people who follow both himself and the woman who posed the question. He also claimed there was not enough space in his Twitter reply to get his fuller argument across.
He added: "Those who thought I was bossily telling a woman what to do rather than let her choose. Of course this was absolutely not my intention and I apologise if brevity made it look that way.
"My true intention was, as stated at length above, simply to say what I personally would do, based upon my own assessment of the pragmatics of the case, and my own moral philosophy which in turn is based on a desire to increase happiness and reduce suffering."
He also argued: "Those who took offence because they know and love a person with Down Syndrome, and who thought I was saying that their loved one had no right to exist. I have sympathy for this emotional point, but it is an emotional one not a logical one. It is one of a common family of errors, one that frequently arises in the abortion debate."
Some Twitter users had supported the God Delusion author, agreeing with his assertion that there is a difference in deciding on a termination before a child is born, and suggesting after the child is born that it should have been aborted.
Many parents of children with Down's, however, took Dawkins to task on Twitter:
Richard Dawkins on Down Syndrome: 'Abort it and try again" http://t.co/1QrMrCtdqo Abort "it"? She was my sister and her name was Becky.— saramo (@saramo) August 21, 2014
My brother is down syndrome Mr Dawkins your saying he shouldn't. Have been born. So hitler had the right idea did he? @RichardDawkins— Lord Snoutintrough (@Rowland72James) August 21, 2014
The Down's Syndrome Association (DSA) also issued a response to Prof Dawkin's initial comment.
They said: "People with Down's Syndrome can and do live full and rewarding lives, they also make a valuable contribution to our society.
"At the Down's Syndrome Association, we do not believe Down's Syndrome in itself should be a reason for termination, however, we realise that families must make their own choice.
"The DSA strives to ensure that all prospective parents are given accurate and up to date information about the condition and what life might be like today for someone with Down's syndrome."
The charity Saving Downs has posted an open letter to Dawkins, with pictures sent in by parents of children with the condition. "Yesterday you chose to publicly judge the worth of people with Down syndrome. It is immoral for you to pass judgement on the worth of others. Fellow human beings who have beautiful lives and are loved members of their families and communities. Our’s is a beautiful kind of love."
"It is immoral for you to attempt to deny the humanity of others by labelling them as an 'it'," the letter continued. "People with Down syndrome are human beings, and have dignity simply by being human. We accept our children for who they are, and are proud to celebrate and enjoy their lives with them. Diversity is good. We love diversity.
"Our families would not be complete without our children. We love them. Please don’t judge them. Through our children we are graced with tolerance and patience. We learn the meaning of unconditional love. Love that has no conditions attached to it. We will stay in the love if that is OK with you. It’s a pretty good place to be."