Salvo issue 15 is sold out so we're going to make some more of the articles available online. This one, in particular, needs to be read.
The Argument Against Abortion
It is wrong wilfully to take innocent human life. The human fetus is an innocent human life. Therefore it is wrong wilfully to take the life of a human fetus.
Almost all attempts to justify abortion challenge not the major but the minor premise. That is, they deny that the human fetus is an innocent human life. One trivial argument challenges the innocence of the fetus, arguing that it is an aggressive invader of the mother's body, and that it is therefore lawful to expel it, however horrible the consequences for it. This is argued by only a few eccentrics, in defiance of the most fundamental principles of justice. For guilt, in law, presupposes moral responsibility, and nobody supposes that unborn fetuses have the mental equipment to be judged legally responsible for their actions. This silly argument may thus be dismissed without further delay.
Most attempts to justify abortion therefore challenge not the innocence but the humanity of the fetus, proposing that it is not "fully" or "truly" human.
These arguments all share one key feature. They require a non-scientific definition of human life. But a human life is definable in entirely scientific, biological, terms: a human life is a living human body. A living human body is physically and genetically identifiable. It is either a whole body (even an embryo is a whole body, although not fully developed) or a damaged whole body (someone who has lost an arm or a leg, an eye or a kidney) that is nevertheless still functioning as an organism.