I write a lot of articles responding to David Boonin for HDI. Most of them are critiques. I want to do something different with this one. I am actually going to defend Boonin because I believe that an argument that he makes gets misunderstood in pro-life literature. As a result, we might be misrepresenting him. Recognizing our potential misunderstandings is important to do because we ourselves often get misunderstood by the pro-choice side and we get rightly annoyed by this. So we should treat people the way that we want to be treated. (Luke 6:31) That means doing our best to understand Boonin’s argument. And when we do misunderstand him, we need to own up to it so we don’t bear false witness (however unintentionally) against him. (Exodus 20:16.)   

For this article, I will do three things. First, I will begin by explaining the argument that the misunderstanding revolves around. Second, I will outline some of the counterarguments to Boonin’s argument. Third, I will show why these responses miss the mark. Fourth, I will offer what I think is a better critique of Boonin’s position.

The Argument 

The pro-life side makes specific ontological claims about what the unborn are. Francis Beckwith writes that “The unborn entity, from the moment of conception, is a full-fledged member of the human community.” (1) Because pro-lifers want to show that our arguments stand up to scrutiny, we of course look for rebuttals in pro-choice literature to defend against. One such rebuttal seems to exist in David Boonin’s book, A Defense of Abortion. In it, he shows that the process of conception takes place over twenty-two hours and is made up of several different stages. (2) 

Beckwith is aware of this point and concedes that there is dispute among embryologists about at which point in the fertilization process a human life (zygote) emerges. (3) Furthermore, he interprets Boonin’s argument as saying that the “dispute about the precise moment at which a new human organism comes into existence counts against the claim that a human being begins at conception.” (4) Scott Klusendorf echoes this understanding when he writes, 

“Philosopher David Boonin discounts the pro-lifers claim that the newly conceived zygote is a distinct, living, and whole human organism. How can this be, he argues, when we don’t know the precise moment during the conception process at which a new zygotic human comes into existence?” (5) 

So how do pro-lifers respond to this? 


There are at least three rebuttals that have been put forward in response to this perceived argument.

The first is that uncertainty over when a zygote comes into being does nothing to refute the pro-life claim that the unborn is, as Hendrik Van Der Breggen describes, “a genetically distinct, self-governing, whole living organism/entity that belongs to the human species.” (6) 

Second, Beckwith writes “It seems to me that Boonin commits the fallacy of the beard: just because I cannot tell you when stubble ends and a beard begins does not mean that I cannot distinguish bearded faces from clean-shaven ones.” (7) In the same way, just because we cannot tell when sperm and egg end and a zygote begins does not mean that we cannot distinguish between human and non-human.

Third, Klusendorf writes,  

“Boonin’s skepticism cuts both ways and serves to undermine his own case. Abortion advocates typically claim that until a fetus has value-giving properties such as self-awareness, rationality, and sentience, it does not have a right to life. But since when can we show the precise moment that those properties come to be in the fetus… No one can say, though abortion advocates suggest that it’s somewhere between twenty-four to thirty weeks. Despite their lack of certitude on these questions, few abortion advocates are willing to surrender their views.” (8) 

Klusendorf’s point is that abortion advocates like Boonin are using an unfair standard. They are claiming we need to be able to pinpoint the exact moment a human comes into existence before we can say it is a human. Yet they do not place the same expectation on themselves. In other words, do they not believe they have to determine the exact moment the baby becomes conscious before they can declare whether the baby has a right to life or not. In fact, they would likely reject that this uncertainty would force them into such a position. 

If Boonin is arguing what Beckwith and Klusendorf are claiming he’s arguing, these would be pretty good rebuttals. However, as I read Boonin’s book myself, something seemed odd when I compared their arguments to his. To that, I’ll now turn. 

Boonin’s Conception of the Conception Criterion 

Boonin knows that pro-lifers believe personhood begins at conception. He believes we choose conception because we think that, unlike in the development of consciousness for example, conception is “the only place where there is a fundamental discontinuity in your developmental history… it is the only place to draw a line between there being a right to life and there not being such a right that makes it non-arbitrary.” (9)

He then puts our argument the following way: 

“P1: The only radically discontinuous event in the developmental history of an individual like you and me is the forming of the zygote at the moment of conception.
P2: If the developmental history of an individual contains only one radically discontinuous event, then the only non-arbitrary place to draw a line along it is at the point of that event.
P3: Morality demands that the line between having a right to life and not having a right to life be a non-arbitrary one.
P4: Individuals like you and me have a right to life.P5: Sperm and eggs do not have a right to life.
C: Morality demands that, in the case of the developmental history of individuals like you and me, the line between having a right to life and not having a right to life be drawn at the moment of conception.” (10) 

After laying all this out, he then goes on to talk about how conception is not a momentary process but one that takes place over 22 hours and has multiple stages. (11)

Problematic Rebuttals

After reading all of this, one thing became clear to me: Boonin was not trying to refute the pro-life claim about what the zygote is. Rather, he’s trying to rebut the pro-life claim about what conception is: namely a momentary, discontinuous event in the life of the human being. 

Therefore, Boonin is not committing the fallacy of the beard. In other words, he is not claiming that we cannot know that the zygote is a human being just because we don’t know at what point in conception he or she comes into being. Rather, he’s trying to show pro-lifers that we’re judging the pro-choice side using an unfair double standard. 

We’re saying it’s unacceptable for them to draw a line for the right to life at an event that is continuous when we are doing the same thing. Given all this, it seems clear to me that Beckwith and Klusendorf misunderstood what Boonin was trying to express in this argument. So where does that leave us?

A Better Way 

There are some steps we can take to clear up the confusion. First, we can admit we misunderstood Boonin’s argument.

Second, we can acknowledge that we’ve used misleading terminology by referring to the “moment of conception.” There are in fact many moments. So, bad on us! (Though since Beckwith and Klusendorf do talk about the various stages, I think they acknowledge this fact anyway.) (12) 

Third, I think we should drop the second and third rebuttals Beckwith and Klusendorf offer. As I said, Boonin is not committing the fallacy of the beard here. Moreover, it is the pro-life side that needs to show we are not using an unfair standard. 

Fourth, we need to state explicitly that Boonin has also misunderstood our argument, and therefore his whole charge against it is a red herring. That is the root cause of why his response does not address the pro-life claim. 

Pro-lifers are not choosing conception as the moment to draw the line for the right to life because it is the only discontinuous event in the development of a human being. Rather, as Patrick Lee writes, it is because at conception “the gametes (sperm and egg) have disappeared and a new human being has come into existence.” (13) This human being is a person, the same person who will “later reason, make free choices, and so on…” (14) and therefore has a right to life. 

To rebut this properly, Boonin doesn’t need to show that conception is a continuous event. Rather, he needs to show that the unborn is not a person like we are claiming.

I’ve written other posts addressing where he’s responded to this issue. It would go beyond the scope of this article to retrace of all that here. For now, it’s worth noting that Boonin already admits this continuity between the embryo and the later human when he talks about his son Eli. He describes pictures he has in his office of Eli during different stages of his life. Finally, he talks about the sonogram he keeps in the top drawer of his desk that was taken of Eli when he was 26 weeks old. (15) He writes, “There is no doubt in my mind that this picture, too, shows the same little boy at a very early stage in his physical development.” (16)                                                   


In this essay, I first outlined how pro-lifers have interpreted Boonin’s argument against the conception criterion. I then outlined how we have misunderstood it and not responded in ways that will further the conversation. Finally, I offered what I thought was a better rebuttal. 

In conclusion, Boonin’s response is a red herring. We are not stating that the right to life begins at conception because conception is a momentary process unlike any other stage of development. We are saying the right to begins at conception because that is when a human person is present. The best way to counter Boonin’s argument is to just keep reminding him of that fact.               


(1) Francis J. Beckwith, Defending Life: A Moral and Legal Case Against Abortion Choice (Cambridge, UK: Cambridge University Press, 2007), xii

(2) David Boonin, A Defense of Abortion (Cambridge, UK: Cambridge University Press, 2003), 37-38.

(3) Beckwith, Defending Life, 66.

(4) Beckwith, Defending Life, 66.

(5) Scott Klusendorf, The Case for Life: Equipping Christians to Engage the Culture (Wheaton, IL: Crossway, 2009), 43.

(6) Hendrik Van Der Breggen, Untanging Popular Pro-Choice Arguments: Critical Thinking About Abortion (Hendrik Van Der Breggen: 2018), 7. Beckwith, Defending Life, 66. Klusendorf, The Case for Life, 43.

(7) Beckwith, Defending Life, 67.

(8) Klusendorf, The Case for Life, 43-44.

(9) Boonin, A Defense of Abortion, 36.

(10) Boonin, A Defense of Abortion, 36.

(11) Boonin, A Defense of Abortion, 37.

(12) Beckwith, Defending Life, 66. Klusendorf, The Case for Life, 43.

(13) Patrick Lee, Abortion and Unborn Human Life, 2nd ed. (Washington, DC: The Catholic University of America Press, 2011), 53. 

(14) Lee, Abortion and Unborn Human Life, 53.

(15) Boonin, A Defense of Abortion, xiii.

(16) Boonin, A Defense of Abortion, xiv.

Cover photo by Eugenia Ai on Unsplash

Born in Vancouver, B.C., Chris has been married to Amy since 2017. He has a BA in Religious Studies (Youth Leadership), and an MA in Theological Studies (Apologetics). He enjoys acting, evangelism, and debates.

The views and opinions expressed in these articles are those of the author and do not necessarily reflect the official position of Human Defense Initiative.