04/07/2013 07:21 BST | Updated 02/09/2013 06:12 BST

Abortion: A Debate About Facts, Not Values

Not too many hours ago a controversial chant was captured on video outside the Texas State Capitol building, whereupon it enjoyed a brief fluttering trend on Twitter before sinking back towards the "and finally" end of the news spectrum...

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Not too many hours ago a controversial chant was captured on video outside the Texas State Capitol building, whereupon it enjoyed a brief fluttering trend on Twitter before sinking back towards the "and finally" end of the news spectrum. Supporters on both sides of the abortion debate stationed themselves inside the seat of Texan government to take part in some good old-fashioned shouty sign waving democracy. One crowd - I'll let you guess whose side they were on - huddled round a conductor and adopted the homely (if bizarrely non-sequitur) tactic of singing Amazing Grace. Their opposite numbers, resplendent in the vivid orange that is the uniform of the Texan pro-choice movement, shouted back "Hail Satan", perhaps partly to highlight their feelings against the intrusion of religion into political debate and partly for the lulz. From what I saw the singers were drowning out the Satanic sardonics, but the footage was taken from within the choir (which was rather like being in the middle of a group of extremely religious emperor penguins) so this impression might be skewed. I won't comment on whether I think this was a clever piece of trolling or a nasty provocation, and either way the story has now sunk back into the annals of the American abortion debate, which seems to thunder on as unceasingly as Jupiter's unsightly anticyclonic acne.

And rather like Jupiter's famous red storm, the debate spins in circles, so we must inject some clarification. The abortion debate, for all its religious to-and-fros, tearful moralising and angry placards is a debate about facts, not values. A debate about values could indeed grind on for millennia without resolution, but in this case the two sides have more in common than many of their supporters suppose.

Everyone in the debate agrees that it's wrong to kill people under ordinary circumstances. Despite some people's attempts to paint Democrats as "pro-child murder", nobody in the debate is actually pro-child murder . This is not a debate about moral values. This is a debate about whether foetuses are persons, which is a factual question. To find the answer some science will have to be done, perhaps looking at foetal brain activity or organ development or viability outside the womb, etc. And then we must not forget the other class of individuals who have rights that must be respected: the parents of these foetuses, particularly the mothers. Once the science results are in and we have a number of weeks at which a foetus legally achieves personhood, then we can start building in extenuating circumstances for abortions after that time e.g. medical emergencies, considering how to limit suffering for both mother and unborn child and find the lesser of any two evils. Therefore it would seem prudent to let the facts decide the issue. Rather than spamming a political discussion with calls to hail this or that supernatural entity the results of scientific examinations of foetuses must be allowed to win the day.

This is not to say that there is no ambiguity involved. What the criteria for personhood are is difficult to strictly define philosophically. I also doubt whether a foetus is not a person one day and a person the next: it seems more likely that personhood will be a sliding scale. But the law can't take account of grey areas like that: when deciding when abortion is acceptable and when it isn't there must be a clearly delineated boundary. The consequence of this is that whatever the number of weeks that is wrestled from the Texas State Capitol, or any governmental body discussing abortion limits, the decision is always going to be slightly arbitrary. This is an inevitable conclusion of trying to map black and white legislation onto a Technicolor reality: there will always be borderline cases.

But what would smooth the process is realising that this is the source of the confusion, not a dissonance of views on murder. Once this is generally understood the debate can come within range of a satisfactory conclusion. And the best part is that, since the law will be built on factual evidence rather than moral principles, if the evidence changes - say because medical science makes foetuses viable outside the womb sooner - then the law can be changed if we need it to be without anybody being forced to publicly admit that they were morally deficient the first time around.

The question is not "Can murdering people be OK?", the question is "Are foetuses people?" And that is a question for science and philosophy to decide - God and Satan can sit down.