What fallacy is this?

Is this a fallacy, if so what fallacy is it?

Fetuses are babies, killing babies is murder, murder is illegal, therefor abortion should be illegal.

or, Fetuses are babies. Is there a fetuses are babies fallacy? It just seems wrong to call a fetus a baby. Seems like its only for emotional reasons. Isnt a fetus defined as pre-born and a baby as post born?

I make this mistake all the time, but I'm often alarmed by the ambiguity of terms proposed in syllogisms as a way of distraction. Dr. Bo offers a really concise explanation of Appeal to Definition as:

Appeal to Definition
(also known as: appeal to the dictionary, victory by definition)

Description: Using a dictionary’s limited definition of a term as evidence that term cannot have another meaning, expanded meaning, or even conflicting meaning. This is a fallacy because dictionaries don’t reason; they simply are a reflection of an abbreviated version of the current accepted usage of a term, as determined by argumentation and eventual acceptance. In short, dictionaries tell you what a word meant, according to the authors, at the time of its writing, not what it meant before that time, after, or what it should mean.

And if I'm not mistaken (which I stand for correction) the First Law of Syllogism is that there MUST be three terms and three terms only (S,M,and P).

Fetuses are babies
killing babies is murder
murder is illegal
therefore abortion should be illegal.

This would appear to violate that law.

Let me spruce up this argument by adding a missing premise and cleaning up the language a bit:

P1. Abortion is killing human fetuses
P2. Human fetuses are babies
P3. Killing babies is murder
P4. Murder is illegal
C. Therefore, abortion should be illegal.

The conclusion logically follows, but most people would have some serious issues with premises #2 and #3. If any of these premises are not true, the whole argument falls apart.

P2 Commits the fallacy of begging the question or arguing in a circle, i.e., assuming the point that needs to be proven, and then using that assumption to prove the point.

There is only one real question in the abortion debate, and that is whether the unborn embryo or fetus is a baby, a human life.

This entail some sub-questions:

a. Does life begin at birth (the traditional view), or at conception (Roman Catholic view), or when the fetus is mature enough to be viable outside the womb (implied by Roe v. Wade)?

b. Does life begin at one exact point? In other words, when we ask "when does life begin," are we asking a reasonable question? B/c the question implies that there is one moment when the fetus is not a life, and another moment when it is a life. Maybe it isn't something that happens at one exact point.

Once agreement is reached as to whether the fetus is a human life, there isn't any further basis for controversy.

Note the emotional loading: anti-abortion people use lots of loaded terms (see theories of general semantics for more info), and saying that the fetus is a "baby" is the most loaded one of all.

At face value, there is no fallacy within the argument. It's primarily an appeal for consistency, in this case protecting babies.

If you, like almost all Americans and people in the world, realize that a woman that's 9 months pregnant has a baby inside and that the baby is alive, and would naturally use the term "baby" to describe that reality, then it's completely rational for someone to appeal for consistency. If that realization extends to 6-9 months post gestation, it's again rational. The rationality extends as far as the mutual realization extends.

If society as a whole generally has that understanding and if it's correct definitionally, it's rational to appeal for consistency. For example, using "define:fetus" in Google results is showing this as the only definition: "an unborn offspring of a mammal, in particular an unborn human baby more than eight weeks after conception."

Merriam-Webster's dictionary gives "an unborn or unhatched vertebrate especially after attaining the basic structural plan of its kind. specifically : a developing human from usually two months after conception to birth "

MedicineNet gives "An unborn offspring, from the embryo stage (the end of the eighth week after conception, when the major structures have formed) until birth."

Where it gets murky is once the mutual understanding of the term breaks down, especially as the fetus gets younger and younger and especially before the baby is actively felt to be moving by the mother.

At that point, it can lead to a fallacy of definition or other fallacies, but a new argument would have to be made for that to be the case. As the argument currently stands, at face value it's a valid and sound argument (although not a syllogism, it can be distilled to one and is actually two arguments in its current state).

Regarding "Isnt a fetus defined as pre-born and a baby as post born?", it has never been defined that way by society as a whole or within the medical and scientific community. Even with a strict biological definition, it's not defined that way. By society as a whole and medical doctors speaking to their patients, it's a "baby" pre-born and it's an umbrella term that goes until toddler stage. Just like child encompasses many ages, "baby" encompasses born and pre-born, with "fetus" as a generally agreed upon stage, especially late-term.

By the scientific community, it's simply a "fetus" and usually the term "baby" isn't used, but sometimes is.

The only time I've heard people explicitly exclude "baby" from pre-born is by "pro-choice" people during abortion arguments, yet those same people often use "baby" for pre-born when not arguing about abortion, which I believe is a fallacy of equivocation by high redefinition during the abortion debate.

It's rare to find someone that doesn't think 9 months post gestation are babies, and ever rarer are individuals that consistently speak that way.

Hi, Jason!

The argument given in your post is a can of worms to evaluate. Here it is, in a vertical layout:

1. Fetuses are babies.
2. Killing babies is murder.
3. Murder is illegal.
therefore,
4. Abortion should be illegal.

The argument is simply not a good one and it is a difficult task to make sense of how this collection of statements is supposed to be coherent.

Until now, no one had questioned the superfluous status of the third premise. Murder is A PRIORI illegal—murder is definitionally an unlawful act. With premise 2 in place, the argument for pro-life can still be valid without the statement in the third premise. We may compact the argument to:

Fetuses are babies.
killing babies is murder.
therefore, abortion should be illegal.

In both its compacted and superfluous form, the argument is invalid because it is an enthymeme; at least one key premise of the argument is implicit. One can recognize this after analyzing the argument carefully. I think that the second premise is a categorical proposition. It claims that all instances of killing babies is murder. And the second premise attempts to support the conclusion by combining with the claim that all abortions are within the category of acts that kill a baby. But how does the argument attempt to convince us that abortion is within the category of killing babies? Stating that a fetus is a baby—premise 1—is not relevant to this end unless the first premise, along with the second, works in unison with another statement: abortion kills a fetus. But this other statement that “abortion kills a fetus” is missing; it is implicit. That is to say, the argument is an enthymeme, and as thus, it is invalid.

From reading over the discussions, it appears that only Dr. Bennett recognized the enthymeme. And the tacit statement he adds is one that he reasonably believes is faithful to the intentions of the arguer. His construction of the argument is:

P1a. Abortion is killing human fetuses [the added tacit statement]
P2. Human fetuses are babies
P3. Killing babies is murder
P4. Murder is illegal [unnecessary premise for the purposes of validity]
C. Abortion should be illegal.

I must emphasize, just as Dr. Bennett had, that the exact claim made by the tacit statement is irrelevant to the critical point that there is a tacit statement. Now, even after courteously being given the key implicit statement, the argument remains invalid and commits a namable fallacy. Dr. Bennett and Nick Savov are mistaken to assert that the conclusion logically follows from the premises (indeed, Savov was especially adamant about his erroneous evaluation to the point that I fear that some of you have bought into it). Much discussion was spent in this forum over a distracted debate on the truthfulness of the premises—I say “distracted” because the missions of rebutting or reinforcing the premises is secondary to the need of checking the argument for fallacies and validity, which was not successfully done. The conclusion of the argument bears a disconnected relationship to what the premise would, if true, prove. The premises of the argument support the conclusion that abortion IS illegal, whereas the arguer pretends that what follows from the supporting statements is that abortion SHOULD be illegal. The argument is not only invalid for this reason, but this devious transition from “what is the case” to “what ought to be the case” is, to give it a name, the is-ought fallacy.

The argument’s premises, with the tacit statement added, should be constructed with the following conclusion:

P1a. Abortion is killing human fetuses
P2. Human fetuses are babies
P3. Killing babies is murder.
P4. Murder is illegal [an unnecessary premise for the purposes of validity]
Ca. Abortion is illegal.

Notice that 'Ca' follows from the premises. What is left in the wake of this readjustment is an argument that is now trivial to the pro-life position. I think it’s very reasonable to assume that the deliverer of the argument in the original post is a pro-lifer, whose aim, in which case, is not to prove that abortion is illegal, but to convince us that the state of being illegal is how abortion OUGHT to be. The original conclusion—abortion should be illegal—is what the pro-lifer wants us to believe, but the premises did not support that particular conclusion. Yet, when the premises are now married to the appropriate conclusion, it is no longer what pro-lifers fundamentally want us to believe. Either way, the argument turns up useless to the aims of the pro-lifer.

Moreover, the third premise is false. As I explained earlier, the third premise is the categorical claim that all acts of killing babies are murder. In other words, the claim is that all acts of killing babies are unlawful, premeditated acts of killing a baby (alternatively: anyone who kills a baby has murdered). The line up of real-world counter examples to this general statement is plethoric: the occasions when a baby died in a car crash or drowned in the bathtub, for instance, in which cases, the killings may occur under unlawful conditions (drunk driving, or negligence, for example) but not premeditated. Or, there are occasions in history in which babies were killed intentionally, but within the legal parameters of the society under which the act was committed, such as when the ancient Spartans left their deformed male babies to die as useless to their war-heavy culture or when a master in recent history might kill a baby slave (which would have been seen only as him causing damage to his own property). Even in contemporary times, if abortion is the killing of babies then not all the killing of babies is murder because abortion is lawful, premeditated killing in some places. Because premise 3 is false, the argument is unsound. The argument is an abject failure. It is invalid, commits at least one fallacy, and contains a false premise. In a word, it is a bad argument.

This concludes my evaluation of the argument, which has significant ramifications against the evaluations of Dr. Bennett and Nick Savov, who both unwarily bestowed a valid status to the argument. Additionally, if the debate in the discussion below, about the truthfulness of the premises, is intended as a way of defending and challenging the argument, then it should come to a halt—indeed, should not have begun, at all—until a valid argument for the conclusion that abortion should be illegal is presented in the first place. I want to continue a discussion that explores strategies for improving the argument, and I already have some thoughts. However, I will hold onto my thoughts on this for a while longer and wait for feedback to this post.

In sum, the original argument is invalid because it is an enthymeme. And when the tacit statement is made explicit, the argument is still invalid and presents the wrong conclusion. The wrong conclusion attempts, fallaciously, to derive an OUGHT from an IS. When the proper conclusion is substituted in, the argument becomes ineffective for the pro-lifers’ purpose. Also, premise 3 is false if it refers to what is unlawful in the human law system. Altogether, the argument is not good. However, there is potential for the argument to be resurrected in a significantly revised form, which is a potential that I would like to share and explore with you all, if you want to discuss it.

Thank you, Jason.

From, Kaiden