My Body My Choice

Both Lives Matter | Blog | My Body My Choice

One of the claims of the pro-choice movement is that the unborn baby is a part of the mother’s body and that in having ownership over her body the mother has a right to do with her body as she chooses. Associated with this is the view that the unborn child is not a person and so not subject to the same moral right to life as the mother in which case there is no moral problem with ending its life. We will explore both of these outlooks in this blog.

Part of the Mother

Reality is made up of things that exist, and these things are made up of parts. Existing things then are composite entities with component parts. Let’s take an example. Water is formed out of the components: hydrogen and oxygen. Water however is something independent of the hydrogen and oxygen. This is clear from the fact that water is wet and can put out fire; something that its components, hydrogen and oxygen, cannot do by themselves. Hence through the composition of hydrogen and oxygen in the correct form we have a new substance which is not identical to its components. Accordingly, when the component parts of a substance come together to form the substance, they are no longer things in themselves but now parts of a new substance. The component parts lose their typical properties and causal powers and allow the new substance to have its own properties and causal powers.

A human substance is itself a composite entity composed of many parts. The pro-choice reasoning suggests that the unborn child is just another one of those parts, in which case the unborn child has the same moral status as any other component part of the mother. If that is true, termination of the pregnancy does not destroy an individual human substance, and so is morally permissible. But this raises problems.

If the child were simply a part of the mother’s body, then the addition of it to her body would entail that the mother ceases to be the human substance that she was and is in turn transformed into a new substance, call it a pregnant substance. To illuminate this let’s return to the water example. Water is H20; two part hydrogen, one part oxygen. If we add to that another oxygen atom, we have two hydrogen atoms and two oxygen atoms H202; this is no longer water but hydrogen peroxide. The addition of some part to an already constituted substance entails a transformation of the previous substance, and this is the case even if the addition is as miniscule as a single atom.

If the child were merely a part of the mother’s body, then the addition of it to her body would be like the addition of another oxygen atom to H2O, i.e. it would transform the mother into something else. But this is not what happens in pregnancy. When a woman becomes pregnant she does not substantially change and become something else; she remains a human substance and only accidentally changes so as to accommodate the pregnancy. This means that the child is not part of her body even though it is dependent on her body. Consequently, what exists in the womb from conception is an independent self-developing human substance, and not a part of the mother’s body. Hence, it has a moral status independent of the mother’s.

The Right to Life

So what moral status does the unborn child have?

A person is a substance of a rational nature. Hence to be a person is to be a certain kind of substance. But the kind of substance it is, is not in virtue of what it does but in virtue of its form, i.e. how it is put together.

So to return to our water example, water is H20, that is its form, it has component parts put together in a certain way; if its parts were put together in a different way, e.g. H2O2, it would no longer be water but would be hydrogen peroxide. Whilst water is H2O it can exist in various different states all the while being H2O. For example, it can be frozen in a solid state, but at room temperature it is in a liquid state. Hence difference of state does not entail difference of thing; the same substance can subsist and display different properties throughout its states.

Insofar as a person is a certain kind of substance, it is put together in a certain way. Now on the basis of its form, a person can perform all sorts of activities depending on the state in which it is. So a fully mature person can think and deliberate given the right dispositions such as wakefulness, sobriety, health etc, but such a mature person cannot do so, if in a different state e.g. asleep, drugged, serious ill-health.

The unborn child is an independent human substance existing in dependence on the mother. Being in a state of immaturity, dependence etc does not entail that it is not the sort of substance that it is, i.e. a human substance. Hence the child, as a human substance, is formed in the same way as the mother, with the only difference being a different state from her. But the fully mature mother is a person, not because of her maturity but because of the kind of thing she is; and the mother is the same kind of thing as the child in which case the child enjoys the same right to life as the mother.

Accordingly, the choice to end the life of the unborn child would be a significant moral choice, inconsistent with the child’s being the same kind of thing as the mother. Therefore, if we recognise that the mother has a right to life, then we ought also to recognise that the child (at whatever stage of development) has the same right to life.


With thanks from all of us at Both Lives Matter to our guest author, Dr Gaven Kerr.

Gaven  has authored a number of peer reviewed articles on various issues in philosophy, and has published a book with OUP, Aquinas’s Way to God (2015) with another forthcoming with OUP in 2019. He is a member of the Dominican Order, and works for the Christian think tank, the Iona Institute.

The views and opinions expressed, are those of the author/s and do not necessarily reflect the official policy or position of Both Lives Matter.