Listening to fellow pundits on the left react with rage and disbelief to the support by the health secretary, Jeremy Hunt, for halving the abortion time limit to 12 weeks, I was reminded of the late Christopher Hitchens. "[A]nyone who has ever seen a sonogram or has spent even an hour with a textbook on embryology knows that emotions are not the deciding factor [in abortions]," wrote the Hitch in his column for the Nation magazine in April 1989. "In order to terminate a pregnancy, you have to still a heartbeat, switch off a developing brain... break some bones and rupture some organs."

It is often assumed that the great contrarian's break with the liberal left came over Iraq in 2003. His self-professed pro-life position, however, had provoked howls of anguish in progressive circles 14 years earlier. It has long been taken as axiomatic that in order to be left-wing you must be pro-choice. Yet Hitchens's reasoning was not just solid but solidly left-wing. It was a pity, he noted, that the "majority of feminists and their allies have stuck to the dead ground of 'Me Decade' possessive individualism, an ideology that has more in common than it admits with the prehistoric right, which it claims to oppose but has in fact encouraged".

Blob of protoplasm

Abortion is one of those rare political issues on which left and right seem to have swapped ideologies: right-wingers talk of equality, human rights and "defending the innocent", while left-wingers fetishise "choice", selfishness and unbridled individualism.

"My body, my life, my choice." Such rhetoric has always left me perplexed. Isn't socialism about protecting the weak and vulnerable, giving a voice to the voiceless? Who is weaker or more vulnerable than the unborn child? Which member of our society needs a voice more than the mute baby in the womb?

Yes, a woman has a right to choose what to do with her body - but a baby isn't part of her body. The 24-week-old foetus can't be compared with an appendix, a kidney or a set of tonsils; it makes no sense to dismiss it as a "clump of cells" or a "blob of protoplasm". However, my motive for writing this is not merely to revisit ancient arguments, or kick off a philosophical debate on the distinctions between socialism (with its emphasis on equality, solidarity and community) and liberalism (with its focus on individual freedom, autonomy and choice), but to make three points to my friends on the pro-choice left.

First, you do realise that the UK is the exception, not the rule? Jeremy Hunt's position is the norm across western Europe: 12 weeks is the limit in France, Germany, Italy and Belgium. Then there's how 91% of British abortions are carried out in the first 13 weeks. You may disagree with a 12-week cut-off but to pretend it is somehow arbitrary, or extreme, or even unique is a little disingenuous.

Second, you can't keep smearing those of us who happen to be pro-life as "anti-women" or "sexist". For a start, 49% of women, compared to 24% of men, support a reduction in the abortion limit, according to a YouGov poll conducted this year. "Polls consistently show... that women are more likely than men to support a reduction," says YouGov's Anthony Wells.

Then there is the history you gloss over: some of the earliest advocates of women's rights, such Mary Wollstonecraft, were anti-abortion, as were pioneers of US feminism such as Susan B Anthony and Elizabeth Cady Stanton; the latter referred to abortion as "infanticide". In recent years, some feminists have recognised the sheer injustice of asking a woman to abort her child in order to participate fully in society; in the words of the New Zealand feminist author Daphne de Jong: "If women must submit to abortion to preserve their lifestyle or career, their economic or social status, they are pandering to a system devised and run by men for male convenience."

Third, please don't throw faith in my face. Hitchens, remember, was one of the world's best-known atheists. You might assume that my own anti-abortion views are a product of my Muslim beliefs. They aren't. (And the reality is that different schools of Islamic law have differing opinions on abortion time limits. The Iranian ayatollah Yousef Saanei, for instance, has issued a fatwa permitting termination of a pregnancy in the first trimester.)

Demonised

To be honest, I would be opposed to abortion even if I were to lose my faith. I sat and watched in quiet awe as my two daughters stretched and slept in their mother's womb during the 20-week ultrasound scans. I don't need God or a holy book to tell me what is or isn't a "person". (Nor, for that matter, do I take kindly to some feminists questioning my right to have an opinion on this issue on account of my Y-chromosome.)

Nevertheless, I'm not calling for a ban on abortion; mine is a minority position in this country. I'm not expecting most readers of The Huffington Post to agree with me, either. What I would like is for my fellow lefties and liberals to try to understand and respect the views of those of us who are pro-life, rather than demonise us as right-wing reactionaries or medieval misogynists.

One of the biggest problems with the abortion debate is that it's asymmetric: the two sides are talking at cross-purposes. The pro-lifers speak about the right to life of the unborn baby; the pro-choicers speak about a woman's right to choose. The moral arguments, as the Scottish philosopher Alasdair Macintyre has said, are "incommensurable".

Another problem is that the debate forces people to choose sides: right against left, religious against secular. Some of us, however, refuse to be sliced and diced in such a simplistic and divisive manner. I consider abortion to be wrong because of, not in spite of, my progressive principles. That I am pro-life does not make me any less of a lefty.

There are few issues that unite Jeremy Hunt, Christopher Hitchens and me. I'm not ashamed to say that abortion is one of them.

This post also appeared on the New Statesman.

Follow Mehdi Hasan on Twitter: www.twitter.com/mehdirhasan