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What If It’s Okay to Kill Innocent People?

We live in a scary age, where intuition no longer suffices to prove the immorality of killing innocent people. A stronger argument is needed.

“Thou shalt not kill the innocent.” Everyone accepts that, right? Think again.

Fifty years ago, Judith Jarvis Thomson didn’t buy it. In her 1971 paper, “A Defense of Abortion,” she explicitly denied the idea that “directly killing an innocent person is always and absolutely impermissible,” calling it “false.” She argued that killing the embryo in the womb, which she conceded is plausibly a human person from conception, is permitted to save the mother’s life.

No idea stays in the ivory tower of the philosopher. This is the standard line of many “pro-life” politicians who claim that life begins at conception but in their policies support legal abortion in cases of rape, incest, and dangers to a mother’s health or life. In other words, sometimes it’s okay to kill an innocent human person.

Such moderation is thrown out the window by abortion advocates like Sophie Lewis. The title of her Nation article says it all: “Abortion Involves Killing—and That’s OK!” She adopts a quote from Maggie Nelson in The Argonauts: “Feminists may never make a bumper sticker that says IT’S A CHOICE AND A CHILD, but of course that’s what it is, and we know it. We’re not idiots; we understand the stakes. Sometimes we choose death”—like in the case of “mothers living in unspeakable conditions” who “kill their children as an act of mercy.”

Mere intuition can no longer suffice to prove the immorality of deliberately killing an innocent human person. Like other long held intuitions (e.g., sodomy is immoral), this intuition is floating away, carried off by the tides of modern thought.

This being the case, we need an argument that’s more stable—something that can be grounded in fundamental moral principles that belong to all of us insofar as we’re human beings.

Is there such an argument? If we take it for granted that the unborn child is a human person, as the above thinkers and writers do, can we argue logically that killing him is wrong? Yes, we can! But it requires a bit of toughing it out to get through it.

Let’s start with this major principle: you’re a human being, and as a human being, there’s stuff that belongs to you. It’s what makes your nature as a rational animal, and therefore is natural to you. And whatever is necessary for you to have that stuff is also natural to you. St. Thomas Aquinas puts it this way: “Whenever a certain thing is natural to any being, that without which this certain thing cannot be possessed must also be natural, for nature is not defective in regard to necessary things” (Summa Contra Gentiles, 3.129).

Consider, for example, that we are by nature social rational animals. We’re not islands unto ourselves. So whatever is necessary for us to live as social animals—you might say, the pre-requisites for living as a social animal—is also going to be natural to us. To deny this would make about as much sense as deploying a soldier to fight with no weapons. It’s the nature of soldiering to fight, and fighting requires weapons, so weapons, just like fighting, are natural to doing what a soldier does.

What is necessary for us to live as a social animal—to live among other rational animals? At a minimum, refraining from killing each other. That is to say, “ordered harmony” (SCG 3.128) is required for us to live out nature’s design for our perfection as social animals. You can’t follow nature’s command to pursue your perfection as a social animal if I kill you, nor can I if you kill me.

The natural order, therefore, entails that each of us be equal in behavior that’s naturally consistent with the exercise of living—what Aquinas calls the “equality of relations” (Summa Theologiae II-II:79:1). So this “equality of relations,” at least with regard to behavior that’s naturally consistent with the exercise of life itself, is natural to us, too. It’s nature’s plan, order, or blueprint. It’s a major part of nature’s recipe for human happiness and perfection.

Here’s where the concept of the innocent comes into play. Being equal in behavior that’s naturally consistent with the exercise of living is just another way of saying the natural order entails that social rational animals be innocent in their relations with one another, primarily in behavior. The behavior itself, even if the person is innocent in will (e.g., a crazy person who’s lost his mind and is not culpable for his behavior), must be consistent with what human nature demands for the “equality of relations” among human beings. So innocence, at least in behavior, is essential to the equality of relations.

Now let’s consider our other major principle: whatever is natural to man is due to him.

Suppose that my country is in a famine. I happen to be well stocked with food and a starving man visits me. Given that food is natural to him as a human being, food is due to him. Seeing that there’s no way for him to acquire food on his own, I would need to give him some. How much? That’s a difficult question to answer, and it goes beyond the scope of this article. But we can say this much: to give him no food, in my circumstances of abundance, would be an injustice. In this moment, it falls to me to give him his due, whether I like it or not.

We showed above that the “equality of relations” among human beings (“ordered harmony”), which at a minimum requires equality in behavior that’s naturally consistent with the exercise of living (me not killing you and you not killing me), is natural to us as social rational animals. We also showed that such equality in behavior is another way of describing innocent behavior. Given our principle above, it follows that being equal in behavior that’s naturally consistent with the exercise of life itself—being innocent in our behavior—is due to each of us. This is why Aquinas writes that “equality in our relations with others” (the peace or “ordered harmony” among human beings) is “the equality of justice” (ST II-II:79:1).

To deliberately kill an innocent human being—a person whose behavior is naturally consistent with the exercise of my life—is to violate the “equality of relations” that is due to him. The killer is no longer equal with the other in behavior. And since such equality is naturally due to an innocent human being—it’s what human nature requires—it follows that to deliberately kill an innocent human being is to violate nature’s plan or order of justice. It would be an injustice on two counts: an injustice done to the innocent human being and at the same time a voluntary failure on the part of the killer to uphold justice—a voluntary failure to give what is naturally due to his fellow man.

Since to behave in a way that violates or thwarts nature’s order or plan for the perfection of human beings is immoral behavior, it follows that to deliberately kill an innocent human being is immoral. And thus, the “thou shalt not kill the innocent” imperative is justified, grounded, and rooted in nature’s order or plan for human behavior.

Now, as we said above, we’re assuming for argument’s sake that a zygote, embryo, or fetus in the womb is an innocent human being, a rational animal that nature directs to live and self-perfect as a social animal. This being the case, the “equality of relations” that is a necessary condition for him to exist as a social animal—an equality of relationship that necessarily involves refraining from deliberately killing him—is naturally due to him. This is what we mean by the fetus’s “right to life.”

And so, to deliberately kill the zygote, embryo, or fetus in the womb is to violate natural justice and thereby to engage in a gravely immoral act—not just because it offends our sensibilities, or “just because,” but for a specific, logically grounded reason. It is an offense against justice, a natural deprivation of the goods to which every human person is naturally entitled.

As regrettable as it is to need such an argument—intuitive horror at killing the innocent should suffice—we live in an age where it falls to us to think through even what seem like the most basic moral propositions. May all people of good will have eyes to see and ears to hear the injustice of the deliberate killing of the unborn.


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