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John's Logic: Science & Philosophy


The abortion debate is filled with all sorts of claims and talking points. Both sides claim that their positions are the most “scientific” as well as morally just, and therefore true. But what exactly do these terms mean? Can the propositions held by either side be morally or scientifically justified? The goal of this piece is to briefly explore the nature of “scientific” and “moral” claims and how they fit into the dispute between pro-lifers and pro-choicers.

But first, it is important that we do not understate how important it is to distinguish between “scientific” and “moral” claims. We need to recognise that there can be no “physics of morality” or “equation of motion for right and wrong decisions”. While bioethics is an example of how science and moral philosophy cross-over, we must bear in mind that the conclusions reached are philosophical in nature as we will see below.

What we mean by science and philosophy


In all fields of study that we consider to be “sciences” the following seem to be common to all of them: they are 1. a system of an orderly classification of concepts which 2. constitute the definitions, divisions and argumentations of some scientific matter.

All of physics, chemistry, biology (and their subfields) satisfy both 1. and 2. For example, in the case of Classical Mechanics you need a firm grasp of vector algebra to be at least competent at vector calculus, which is needed to understand the finer details of Newtonian mechanics in its numerous applications. You must understand the basics before the advanced material, and within these are definitions, distinctions and argumentations (be it mathematical proofs or experimental methods).

The same applies to the biological sciences. In the case of embryology, you first need to know what embryology is, understand concepts such as gametes (sex cells) and the minor distinctions between embryos, zygotes, fetus’ etc. In order to be a competent embryologist you need to have a firm grasp of the theory as well as the relevant experimental methods and arguments. Hence, when people commonly use the term “science” in abortion issues, they usually mean the experimental (or natural) sciences.


Now, what is philosophy? It can be defined as the science of things through their first fundamental causes (or reasons) under the light of human reason. In other words, it is the study of the fundamental nature of knowledge, reality, existence, and human actions. Like biology, it is a science insofar as the subfields of philosophy (metaphysics, epistemology, moral philosophy etc.) are systems of concepts classified in a certain order, which consist of definitions, divisions, and argumentations.

Philosophy uses arguments distinct from that of biology, but it is nonetheless a “science” in the aforementioned sense.

Now, which subfields are relevant to the abortion debate? While this list is not exhaustive, the common arguments principally concern questions of morality and metaphysics. This is because the two principal questions of the issue are:

Number one: What is the developing thing in the womb?

Number two: Is it permissible for anyone to kill it?

How philosophy & science intersect

So how are the two related?

There are generally two opposing positions in the abortion debate, both of which with often opposing answers, as shown below:

Pro Choice:

1. What is the thing developing in the womb?

  • Some deny that it is a human being.

  • Some concede that it is a human being, but deny that it is a person.

  • Some concede that it is both a human being and a person.

2. Is it permissible for anyone, woman or not, to kill it?

  • Some answer yes, but justify their answer with appeals to bodily autonomy. These usually concede that the thing developing in the womb of a pregnant woman is a person.

  • Others answer yes, but appeal to the certain qualities that the developing thing currently lacks.

Pro Life/Anti-Abortion:

1. What is the developing thing in the womb?

  • Some affirm that it is a human being, but a potential person.

  • Some affirm it is both fully human and a full person, with no real distinction between the two. This seems to be the mainstream view.

2. Is it permissible for anyone, woman or not, to kill it?

  • The majority of pro-lifers affirm that it is never permissible for anyone, woman or not, to intentionally kill the developing human being in order to end a pregnancy. This is the case for those who believe that the developing human being is a potential person, as well as those who believe it has full personhood.

As we can see from above, the answers to number one can be either be scientific or philosophical, whereas the answers to number two can only ever be philosophical. The reasons for this are as follows:

With regard to number one, the term “human being” can either mean a “living organism with human DNA”, which is a purely biological definition, or some metaphysical definition such as “a being with a rational soul that could potentially use the powers natural to it” i.e. a being that has the potential to do form relationships, reason etc. without necessarily using those abilities. Furthermore, “person” is not a biological term, for even if you were to define it in scientific terms it would be identical to what is meant by “biological human being”.

With regard to number two. answers to this question consist of non-scientific terms. In fact they concern what “should” or “should not” be done, which is not a matter of biology but of morality and therefore philosophy.

When to use philosophy & science

So what is the point of all this? From the previous section it is clear that not only are science and philosophy called upon when answering the main questions, but also when justifying the answers. This brings us to the main points, which are:

  1. Science and philosophy can be used, together, in arguments for why abortion is morally wrong or permissible (as seen above).

  2. Science alone can never justify answers to number two. In other words a moral claim (a claim regarding what is or is not okay or permissible) cannot be justified by purely scientific reasons.

Why is point B true? Suppose we wish to defend the moral claim “Abortion should not be done” with purely scientific reasons. We could appeal to biology and give the following argument:

  1. Abortion kills young biological human beings.

  2. Therefore, abortion should not be done.

The problem with this argument is that either the argument is logically invalid, or we must insert a second premise such as “the killing of young biological human beings should not be done”. If the former is true then we do not have a good, valid, pro-life argument. If the latter is true, then we have a valid argument but at the expense of appealing to a moral claim. Since we want to give good arguments, we must therefore affirm point B.


All this is to show the limits of our appeals to science. Science, on its own, can only defend purely scientific claims. We therefore cannot simply say that the pro-life, or pro-choice, positions are “scientific”. Furthermore, as pro-lifers we cannot say that abortion is wrong because of “science”, and leave it at that.

Both are moral positions. As such, their claims are of a moral nature. Therefore while we can appeal to scientific data, we must bear our own moral assumptions in mind.

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