Philosophers Alberto Giubilini and Francesca Minerva have received an avalanche of abusive comments and emails following the publication of their paper on “post-birth abortion” in last week’s Journal of Medical Ethics. The response has been despicable but it shouldn’t blind us to the flaws in the authors' argument.

As the journal’s editor Julian Savulescu noted, their arguments “are largely not new and have been presented repeatedly … by the most eminent philosophers and bioethicists in the world.” But the discussion has continued because it’s been notoriously difficult to prove the arguments wrong.

Giubilini and Minerva’s argument is stunningly simple. There is no morally relevant difference between a foetus and a newborn baby, because their capacities are relevantly similar. Neither foetus nor newborn is really capable of forming any long-term aims. Only a person can form long-term aims that are capable of being quashed – and this is what differentiates us from other species – so neither a foetus nor a newborn are persons.

The kind of harm that consists of preventing a person from achieving their future aims is especially acute. And since neither a foetus nor a newborn are persons, they cannot be harmed in this way. Therefore, if we allow abortion on that basis, we should allow infanticide.

Many people who believe abortion should be permitted would reject the conclusion that killing a newborn baby should likewise be permitted. The challenge is to explain why the rejection of that conclusion is not irrational. That’s what I will attempt here.

The wrong of infanticide

First, we need to broaden the notion of aims so it includes immediate preferences and desires. As any mother will attest, a newborn baby has immediate preferences and desires that he or she wants satisfied, such as the need to suckle the mother’s breast. Why shouldn’t these shorter term desires count equally to the longer-term preferences of persons?

The problem with that response, the argument runs, is that it would apply equally to many other species that we don’t think twice about killing.

For consistency’s sake, it is said, we must adopt the narrower concept of person favoured by the authors, or we are guilty of speciesism (and speciesism is as bad as racism).

What makes humans different from most of the animal kingdom is precisely our capacity to form long-term aims that can be quashed. This makes us capable of suffering a kind of harm that other beings aren’t capable of suffering. That’s why it can be wrong to kill humans, but permissible to kill some animals.

But if we relax this criterion to include immediate preferences and desires of infants, then we have to give up killing animals and, on some views, even some insects. This drives the authors to assert that we do no wrong to a baby if we kill it.

Is there another way of approaching the problem? I think there is. We can deny the analogy between racism and “speciesism”. There is something primal about protecting our own flesh and blood, about the value we place on their wants and needs.

The authors might say: “so what? Why is that relevant? Emotional bonds have no place in moral discussion, for how we feel about a child doesn’t tell us how we ought to feel about it.” But the point is that there is a limit to the kinds of practices we can meaningfully subject to moral scrutiny.

Caring for our offspring is as much a natural fact about us as walking upright, so it makes no more sense to question whether we ought to do this than it does to question whether we ought to walk upright. True, there are occasions where the mother does not bond, but this is unusual. It does not mean that care for our offspring is not a fundamental feature of our humanity.

These natural facts can serve as the basis for the erection of moral norms, such as the norm that we ought not to kill our offspring. This is unlike racism, which is nowhere near as endemic or universal in human life as the instinct to care for our offspring.

But the authors might retort: infanticide has been more widespread in human history than it is today, and is still practised in some places. This might be true, but it is misleading.

In hunter gatherer societies, infanticide was practised out of material necessity of the kind we can only imagine today. If more young were born than could be suckled, or offspring with cerebral palsy were born, what could those societies meaningfully do? The options open to us today were not available in such societies. This should not be ignored.

We also should not ignore the level of ceremony and grief that accompanied the practices, which is an acknowledgement that if things could have been otherwise, the practice would not have been engaged in. So the practice of infanticide in the past doesn’t mean that the instinct to care for our offspring does not run deep in us – so deep as to be beyond question.

This instinct leads us to erect the rule that it is wrong to kill our children. It explains why we care for their wants and needs, while not valuing the wants and needs of other species in the same way.

We can therefore accept the narrow definition of person the philosophers prefer, but conclude that it isn’t the only determiner of value.

The role of emotion

Philosophers are prone to over-rationalising things. The emphasis on reasoning might blind them to its limitations, leading them to neglect the important role emotions play in our moral framework.

Consider the harrowing story of Dr Brian Hoolahan, a Nowra obstetrician who repeatedly witnessed babies taken for adoption from their unwed teenage mothers moments after birth, between the 1940s and 1970s: “I remember the girls calling out ‘I just want to touch my baby, please let me see my baby’ and they were crying and howling and it was the most horrific thing I’ve ever seen in my life.”

Faced with this testimony, it is a bit easier to see why the value of a baby’s life cannot be intellectualised in the way that philosophers would have it, and why capacities are not the only thing of moral importance.

The pain, anguish and unimaginable enduring grief these mothers suffered all go to show the meaning of having a baby in human life, the central place it has in our emotional make-up. These instinctive responses to the birth of one’s child are the sources of its moral value. It is senseless to ask if these mothers really ought to be having that kind of response to their children.

Not every mother wants their child. But this doesn’t mean the child is of no value. The norm we have erected, based on the instinct shared by the majority of us, means we condemn such mothers if they seriously want to kill their babies.

Perhaps if the majority of us no longer wanted our children, we would abandon the norm. But that’s not how things are.