Logical Arguments Against Abortion: Part 1

Valid logical arguments show that one does not have the right to commit abortion

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Earlier, I presented a logical argument showing that consent to sex does constitute consent to any naturally resulting pregnancy. That article was written specifically in response to the common refrain from the pro-abort crowd that “Consent to sex is not consent to pregnancy.” Here, I would like to simplify that argument by breaking it up into smaller, more manageable arguments. The end result is the same, however, as one would expect since these are well-supported logical arguments, and any set of well-supported, valid logical arguments are not contradictory.

Let me begin by discussing what it takes to make a valid logical argument, and what it takes to make a valid argument which has a conclusion that must logically be true. You see, not all valid arguments yield conclusions which are true (as I will show below). OK, here is an example of a valid argument:

P1: All humans are mammals.

P2: George Washington was a human.

C: Therefore, George Washington was a mammal.

Clearly, this argument is not only a valid argument, but it has a conclusion that is true. How do we know that the conclusion is true? We have confidence that the conclusion is true, because BOTH of the following conditions are met:

1. The argument is a valid argument. In other words, the conclusion follows logically from the stated premises – that is precisely what we mean when we say that it is a valid argument.
2. The two premises are true.

If an argument is valid, and the premises upon which the argument is based are true, then the conclusion must also be true.

Now let’s take a look at an argument that is not valid – one in which the conclusion does not follow from the premises:

P1: All humans are mammals.

P2: George Washington was a human.

C: Therefore, George Washington was the first President of the United States.

While both premises are true, and the conclusion happens to be true also, the argument is not valid. You cannot come to the conclusion that George Washington was the first President based on the premises. The premises do not lead to the conclusion, so the argument is invalid – even though all three elements are true statements.

Here’s another invalid argument that’s a little more subtle:

P1: Some mammals are humans.

P2: George Washington was a mammal.

C: Therefore, George Washington was a human.

While the premises and conclusions are all true, the argument is not valid. For an argument to be valid, the conclusion must follow inescapably from the premises. That is not the case for this argument. If we knew nothing about George Washington except what the premises tell us, we could not be sure that George Washington is a human because not all mammals are humans. Only some of them are. For all we know, “George Washington” might be a dog and be a mammal, but not a human. Thus, the argument is invalid because the conclusion does not necessarily follow from the premises.

Now, let’s show a valid argument that is false:

P1: All humans are amphibians.

P2: George Washington was a human.

C: Therefore, George Washington was an amphibian.

Clearly, this conclusion is false. However, you should note that the argument IS a valid argument. IF both premises were true, then the conclusion would also be true. Unfortunately, the first premise (P1) is not true, and so the conclusion is false.

In general, one can only say that since the premise is false, the argument does not show that the conclusion is true. It is possible that the conclusion may be true coincidentally. Here is a hypothetical example:

P1: All humans are male.

P2: George Washington was a human.

C: Therefore, George Washington was male.

Clearly, the conclusion IS true, but the first premise (P1) is obviously false. So the fact that the conclusion of this argument is true is merely coincidence.

Let’s review. If the conclusion of a logical argument follows directly from its premises, we consider the argument to be a valid logical argument, and in that case, the truth of its conclusion rests upon the truth of the stated premises. If the stated premises of a valid argument are objectively supported by observation (or science) or by the conclusions of other valid logical arguments which are objectively supported, then we consider the conclusion to be true.

The truth of these conclusions do not rest merely on opinion, doctrine, or religious texts. Instead, these conclusions rest directly upon logic and science.

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Now that we have reviewed logical arguments, let’s apply this knowledge to the abortion debate. Here is what I consider to be the most basic argument, and I will refer to it as Argument 1:

P1.1: One does not have the right to kill an innocent human being.

P1.2: A child not yet born is an innocent human being.

C1: Therefore, one does not have the right to kill a child who has not yet been born.

Stated this way, it is difficult to imagine how any sane person would object to the truth of this conclusion. Clearly, the conclusion (C1) follows directly from the two stated premises (P1.1 & P1.2), and so this IS a valid logical argument. In addition to this, the premises of this argument are true. This means that we can have confidence that the conclusion is in fact true.

Of course, P1.1 cannot be proven to be true using science because such things as human rights do not fall within the purview of science. However, this principle – that one does not have the right to kill an innocent human being – is widely accepted as true among civilized societies and was specifically addressed by the Founding Fathers in the Declaration of Independence when they pointed out that it is “self-evident” that all humans possess certain unalienable rights, including the right to live.

Of course, the second premise (P1.2) is objectively shown to be true. In defense of that statement, let me address three important elements of this premise. First, one cannot object to my use of the term “child” here because “child” universally means “son or daughter,” and a child who has not yet been born is a son or daughter. That fact is simply undeniable, and it is this meaning that is used here. Second, that this child is indeed innocent is evident because he or she has not had the opportunity to commit any crime worthy of death. And third, the fact that this child is a human being (defined as a member of the human species) is abundantly clear since there is no possible way that two human beings can produce an offspring that is not also a human being.

Now, let me turn to the second most fundamental argument, which I will call Argument 2:

P2.1: All innocent human beings possess the exact same right to live as any other human
         being.

P2.2: A child not yet born is an innocent human being.

C2: Therefore, a child who has not yet been born possesses the exact same right to live
       as any other human being.

As before, the first premise (P2.1) is not one that can be supported with science because (again) the subject of human rights does not fall within the purview of scientific investigation. However, in order to argue that this premise is false, the critic must take the bigoted position that some human beings (like themselves) possess human rights that other human beings (those they wish to be allowed to kill) do not have. Furthermore, one can see that the second premise (P2.2) is identical to P1.2, and so has the same justification.

Therefore, since the conclusion (C2) follows directly from the premises, Argument 2 IS a valid logical argument, and so, like Argument 1, we have confidence that the conclusion is in fact true. Thus far in this article, we have shown that the following two statements are true:

C1: One does not have the right to kill a child who has not yet been born.

C2: A child who has not yet been born possesses the exact same right to live as any other
       human being.

As you can see, these two well-proven truths alone are sufficient to show that abortion is a violation of the right to life of the child being aborted. Surely, any rational person will agree that if these two statements are true, then it should not be legal to commit abortion.

Notice that these two conclusions are not based in any way upon consent to sex. This means that they are true in general and are not subject to consensual sex. Whether or not the mother has consented to sex is not even addressed at all in these two arguments. These two arguments demonstrate logically that, regardless of the circumstances, children who have not yet been born have the same right to life as those of us who have been born. Thus, birth does not convey the right to live, and neither does any other event in an individual’s life. This right must come into existence when the human individual comes into existence, and that happens at fertilization (as we have shown earlier).

In Part 2, I will apply this logical method to the subject of consensual sex and show that consent to sex is indeed consent to pregnancy.