The evolutionary biologist and philosopher Richard Dawkins created a Twitterstorm this week when he posted about a young woman in Ireland who was forced to give birth to a baby conceived through rape.
She was suicidal but health officials refused to grant her a termination and this week the baby was born by C-section and taken into the care of the state.
Dawkins said Ireland is a civilised country except in women's reproductive rights, and a conversation among his followers ensued. One woman tweeted that she wouldn't know what to do if she were pregnant with a Down syndrome baby and Dawkins said she should abort it and try again.
So far, so in keeping with his beliefs. He doesn't believe fetuses have human feelings or rights, so if a woman decides she doesn't like the fetus she's carrying, get rid of it and start again. A bit like stripping the wallpaper in the lounge.
Then he came unstuck. What about people on the autism spectrum, one tweeter asked, adding that she was autistic. Dawkins replied: "People [on the autism spectrum] have a great deal to contribute. Maybe even an enhanced ability ... People with DS are not enhanced."
Wow. Quite the judgment call. I wonder how many people with Down syndrome Dawkins has met. Not many, I'd hazard a guess.
The people with Down syndrome I have met have certainly enhanced my life. To be fair, I've had the benefit of their company for only a matter of hours.
And I understand that when a child is born who is different you will worry and agonise about their future, as does a parent with a child born "normal".
I can understand an evolutionary biologist believing in survival of the fittest, but when he starts making judgments about which humans enhance life and which do not, surely that moves him away from his foundation of logic and reason.
There are people on the autism spectrum who have fulfilling lives and enhance the lives of those around them and there are people on the autism spectrum who do not.
The same is true of people with Down syndrome. By suggesting that some fetuses are more valuable than others Dawkins appears to be moving into eugenics, not evolution.
He insisted, as the twitterstorm broke, that he was not questioning the right to live of people with Down syndrome who have already been born — just those who have not yet been born. "There's a profound moral difference between 'This fetus should now be aborted' and 'This person should have been aborted years ago'," he wrote.
But his comment that people with Down syndrome don't enhance the lives of those around them or the general community indicates he hasn't spent time around people with Down syndrome.
I feel sure that if he did he would abort his theory — and try again.
• Kerre McIvor is on Newstalk ZB, Monday to Thursday, 8pm to midnight.