Pro-Life People: When Debating Abortion, Avoid This Embarrassingly Common Logical Mistake

Opinion   |   Tim Brahm   |   Jun 24, 2015   |   4:57PM   |   Washington, DC

Don’t you hate it when your honest clarification question is mistaken for the start of a fallacious argument? Almost every time in the last year I’ve talked with pro-choice students at a pro-life outreach, I’ve had an exchange that goes something like this:

Pro-Choice Student: The fetus isn’t even a person.

Tim: We agreed earlier that a newborn is a person. Do you think a fetus is a person right before birth?

Pro-Choice Student: *sigh* I know where you’re going with this, you’re going to try to trap me by asking if it’s a person right before that, or right before that.

Tim: No! I’m so glad you said that because that gives me the opportunity to clarify. The argument you’re describing is a logical fallacy, it’s one of the worst pro-life arguments I’ve ever heard, and if any pro-lifer out here makes that argument, I’ll prove them wrong on your behalf. I’m not trying to trap you, I’m just trying to figure out what your position is. What is it that makes us persons?

Unfortunately, because of how common this pro-life mistake is, the pro-choice student is expecting our conversation to go something like this:

Pro-Choice: The fetus isn’t a person.

Pro-Life: When do you think it becomes a person?

C: It isn’t a person until it can think.

L: So would you say it’s a person at birth?

C: Sure, it can think at birth.

L: Well, how about the day before it’s born?

C: I don’t know, maybe.

L: How about the day before that?

C: I think I see where this is going…

L: And how about the day before that? You just have to push back a little at a time to prove that there isn’t a difference between a newborn and a fetus. If the newborn is human, and there isn’t any big change in any day of its development, then it must have been human at the beginning.

C: Well I think there’s a big difference between the day it can think and the day before that.

L: Okay, then let’s talk about the day it can think. How about one second before that? The difference in the fetus from second to second is miniscule. So how can you say it is not human one second and human the next?

C: I don’t know how to explain it but I’m not persuaded.

While making what sounds to some pro-life ears like a very persuasive and reasonable argument, the pro-life person in this example has fallen into a logical fallacy called the Continuum Fallacy, more commonly known as the fallacy of the heap or the fallacy of the beard. This fallacy takes place when you attempt to demonstrate that two states cannot be distinct because there is a continuum of states between them.

That might be confusing. Stay with me, I’ll explain with a very easy-to-understand example.

In my opinion, the easiest way to understand why a type of reasoning is fallacious is to see that reasoning applied to something more obvious, and then see the consequences. Let’s apply the same continuum reasoning to President Lincoln’s beard:


Beard Believer: Lincoln obviously has a beard.

Beard Skeptic: Oh really?! When do you think a beard becomes a beard?

Beard Believer: I’m not sure. Certainly it’s a beard when it’s an inch long.

Beard Skeptic: Well, what if he expertly trimmed his beard down by one millimeter? Would he still be furry enough to qualify as “bearded?”

Beard Believer: Yeah, sure, I guess.

Beard Skeptic: What about one more millimeter?

Beard Believer: Yeah…

Beard Skeptic: And what about one more millimeter?

Beard Believer: I think I know where you’re going with this…

Beard Skeptic: And one more millimeter after that? What if he’s down to stubble? What if we remove the stubble and now he’s clean-shaven? Unless you can clearly delineate the exact moment Lincoln no longer has a beard, and give an argument for why that moment is not simply arbitrarily chosen, we must conclude that there is NO difference between Lincoln’s beard in this picture and a clean-shaven woman! Therefore if Lincoln has a beard, EVERYONE, MAN OR WOMAN, HAS A BEARD!!!

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If you aren’t familiar with the continuum fallacy, it’s awfully hard to argue with the skeptic’s conclusion. But of course we know that Lincoln has a beard and we know that if someone is clean-shaven, they don’t have a beard. We know that even if we aren’t sure exactly how much facial hair one must have in order to qualify as having a beard, we generally know one when we see it. Just because there are some cases when it isn’t obvious whether a given person is bearded, that doesn’t mean we cannot ever recognize the difference between a bearded person and a non-bearded person.

Similarly, it doesn’t follow that because a pro-choice person cannot determine where the dividing line is between a valuable human infant and (in her mind) a non-valuable human zygote, that does not mean that there isn’t a difference. I don’t think there is a morally relevant difference between the two; I just don’t believe that can be demonstrated by asking “what about one second before that?” over and over. I agree with the conclusion of this pro-life argument, but this isn’t a logical way to get to the conclusion.

You might be wondering, “does anyone even make that illogical argument?” The answer is yes. I’ve heard it from many pro-life people, I’ve seen it in pro-life blog posts, and I’ve even seen it in at least one Christian pro-life movie. It’s especially common for pro-life people to turn to this argument when they feel stuck, like the argument is a safety net. I don’t want to name names or call anyone out, because the pro-life movement doesn’t need more division. But we do need to stop making this bad argument.

You might be thinking, “but come on, it is totally fair to call the pro-choice person to task if they can’t explain the difference between a human you can kill and a human you can’t!” And I agree!

This fallacious pro-life argument is driven by a question that is perfectly fair to ask IF it is used in the context of shifting the burden of proof. Let’s return to Lincoln’s beard for a moment. Suppose someone were to say that she thought that it was morally justified to kill anyone with a beard. Suppose then that they refused to give any kind of explanation for when someone has a beard and when they don’t. That would be a big problem! If you’re going to advocate for the right to kill a group of humans, it seems reasonable to expect you to be pretty clear about which humans are in that group.

The fact that there is a continuum between two states does not necessitate that there is no difference between the two states. But if you are going to claim that someone on one side of the continuum has the right to life and the person on the other side of the continuum does not, it is reasonable to demand some explanation.

The pro-lifer should ask what the difference is, and point out how odd it is that a woman can legally kill her third-trimester unborn just days before it is born, and how it doesn’t seem like there is a relevant difference between the third trimester unborn and the newborn. But he must not erroneously claim that there cannot possibly be a difference simply because there is a continuum of states between the two. And if you recognize that a pro-choice person thinks you’re making this mistake, clarify what you really mean, and that you wouldn’t use such poor reasoning.

LifeNews Note: This post originally appeared at the Equal Rights Institute blog. Click here to subscribe via email and get exclusive access to a FREE MP3 of Josh Brahm’s speech, “Nine Faulty Pro-Life Arguments and Tactics.”