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On December 14, the United States Conference of Catholic Bishops issued a response to a question that many Catholics had recently been asking: Is it permissible to get vaccinated for COVID-19 if the development of the vaccine involved cell lines derived from aborted fetuses? The USCCB’s answer was that the use of such “morally compromised cell lines” was a form of material cooperation with evil. While it would be better to develop vaccines that do not involve these cell lines in any way, the bishops concluded that it is nevertheless permissible to use the current vaccines, given that the cooperation with evil is remote and that the benefits of vaccination are so great.

The USCCB’s statement faced an immediate blowback in some pro-life circles, and several bishops signed an open letter lamenting that “the acceptance of these vaccines by Catholics, on the grounds that they involve only a ‘remote, passive and material cooperation’ with evil, would play into the hands of the Church’s enemies and weaken her as the last stronghold against the evil of abortion.” The letter even argued that the rush to vaccinate demonstrated that “our society has created a substitute religion: health has been made the highest good, a substitute god to whom sacrifices must be offered—in this case, through a vaccine based on the death of another human life.” The letter ended with a claim to the sensus fidei, describing the “almost instinctual” reaction against the vaccines among laypeople with whom these bishops had spoken.

Catholic moral theology does not usually give much weight to “instinctual” reactions, and for good reason. They are sometimes based on bad information. In this case, it quickly became clear that many in pro-life circles did not actually understand what exactly the connection to abortion was. The open letter spoke of one’s own “body” benefiting from the “fruits” of this “concatenation” with the “abortion industry.” It encouraged the lurid idea that, as one well-known pro-life commentator put it, the bishops were allowing “our children to be injected with these vaccines that have dead children in them.” Such sensationalistic language implies that all the talk about “remoteness” is just a smokescreen for a moral abomination.

Happily, the USCCB’s own analysis eschews such sensationalism. It soberly recognizes the importance of vaccination for our whole society, as does the subsequent instruction issued by the Vatican on December 21. Still, many readers of Commonweal might find the USCCB document excessively cautious and the later Vatican document even more so. It might seem obvious that the benefits of a COVID vaccine outweigh any concerns about the use of “cell lines of illicit origin,” as the bishops call them. But what if the cells used had come from the HeLa line, the first “immortal” cell line still used for much research, obtained by Johns Hopkins in the 1950s from a young female African-American cancer patient without her consent?

The vaccine controversy raises the larger question of how to evaluate the present use of benefits derived from past evils. This is a difficult question that many people want to make too easy. They perform utilitarian calculations when they are less concerned with a past evil, and demand maximum moral purity when they are more concerned. The USCCB, to its credit, speaks out of the rich Catholic tradition of reflection on these knotty questions. But its approach also raises some questions about that tradition’s viability in light of the whole range of grave historic wrongs on which our lives are built, from slavery to abortion.

Picking up on Dignitas Personae, a 2008 document issued by the Congregation for the Doctrine of the Faith, the USCCB and Vatican statements on vaccination use the framework of cooperation with evil. The traditional casuistry related to this idea assumes that one’s action contributes, either formally or materially, to the evil action of another. What’s called “formal cooperation” involves sharing the evil actor’s intent. Think, for example, of an accomplice to a conspirator who supports the conspiracy by keeping its secrets. This is always wrong, as should be obvious. The real difficulties come under the heading of “material” cooperation, such as the classic case of the cab driver who is asked to take a fare to the address of a well-known brothel. This, too, is to be avoided, but there can be many good reasons to accept material cooperation in some cases, not least because there are so many differently positioned cooperators. The sheer scale and complexity of large social structures can make judgments about material cooperation very difficult, but writers such as Julie Hanlon Rubio and Daniel Finn have attempted to develop the concept especially in terms of our agency as consumers. They (and I) are convinced that Catholics must still ask serious questions about sins of material cooperation when making individual choices, even in very large and apparently impersonal economic and political systems.

You might wonder, what exactly is the material cooperation in the case of the new COVID vaccines? At its best, Catholic moral analysis relies on accurate descriptions of acts; and the act in question here is receiving a vaccine whose development made use of cell lines of illicit origin. Note that the USCCB letter is evaluating not the act of abortion, nor the use of cells taken from fetal tissue, nor the vaccines that include such cells, but rather vaccines whose process of production or testing includes the use of cells taken from a cell line (HEK-293) that is virtually ubiquitous in basic medical research. The cells used to start this line back in the 1970s were taken from an aborted fetus.

Readers may already sense the awkwardness of using the term “cooperation” in a case like this. What we are really talking about is appropriation of the fruits of an evil act. In a scholarly article published twenty years ago, Cathleen Kaveny pointed out that attempts to force instances of appropriation into the framework of cooperation often end up getting things backward. This is because, in cases of appropriation, you are not helping the evildoer; it is the evildoer who is (unintentionally) helping you.

The two main approaches to the problem of appropriation—one a demand for an unrealizable purity, the other a cold-blooded utilitarian calculation of results—both seem inadequate in light of a key fact: the past is past; what’s done cannot be undone. To take an example of continuing importance in this country, there is no way for Americans to “make up” for slavery, and no way to sever the chains of causation that still link us to that abominable institution. The same thing is true about an awful lot of medical and biological knowledge. I recently read Bill Bryson’s The Body, and I was struck by how much basic medical knowledge and how many medical procedures were developed in ways that would horrify us now.

We need a better framework for dealing with problems of appropriation. Consider two places where the USCCB’s analysis falls short because it relies on the existing tools designed for evaluating cooperation with evil. First, in a key passage, the bishops say “it is important to note” that its examples of “morally-compromised vaccines” do not in fact rely on any new abortions, or create any demand for them. Quite the contrary: HEK-293, the “immortal” cell line used in the development of the COVID-19 vaccines, lasts indefinitely, and experimenters often prefer using familiar, often-deployed materials to make it easier to compare results. If anything, HEK-293’s ubiquity in basic research likely forestalls the development of newer cell lines. Yet, while the document says this is “important to note,” it does not say why it is important to note, and it goes on to analyze the use of these cell lines as “morally compromised.” Readers are left with the impression that the cell lines are themselves still somehow tainted by abortion, but what does that mean? On exactly what grounds is some material labeled “morally compromised”?

This quasi-physicalist suggestion of a tainted object is amplified by a second aspect of the USSCB’s analysis: an apparent moral distinction between, on the one hand, the Pfizer and Moderna vaccines and, on the other, the vaccine developed by AstraZeneca. What is this distinction? As indicated in a chart widely circulated by the Lozier Institute, the first two (mRNA) vaccines do not use HEK-293 cells in their design and production, only for testing. The AstraZeneca vaccine, by contrast, requires the use of HEK-293 cells in all phases of its development. The USSCB statement explicitly states that the first two vaccines are therefore morally preferable, but then, acknowledging that many people may not be able to choose which vaccine they get, the statement goes on to encourage Catholics to get the AstraZeneca vaccine if that’s the only one available to them.

This analysis risks causing unnecessary confusion among the faithful, not least by fostering the idea that the vaccines themselves are measurably tainted—an idea that plays into the hands of the zealots. Is there really a morally significant difference here? Isn’t it the case that using the cells is either “morally compromising” or not? It’s as if the moral stain is greater in one case than in the others simply because there is more cooperation, as “measured” by the Lozier chart. In typical cases of cooperation, attempts to distinguish between alternatives would prompt closer attention to a variety of characteristics linking the cooperator with the evil act. But the distinctions the bishops are making seem encouraged by the Consumer Reports quality of the Lozier Institute chart, which uses red and green indicators in various boxes, thereby reducing the moral analysis to a kind of checklist. To be fair to the Institute, the chart provides accurate and valuable information about the various vaccines, but the color-coding approach suggests that morality is a matter of evaluating products, when it’s really about evaluating intelligible actions.

While the new Vatican document does not propose moral comparisons among the various COVID-19 vaccines, its use of the ill-fitting category of cooperation manifests a different problem: it encourages the idea that conscientious objectors to vaccination are morally heroic. After all, while “remote material cooperation” can be permissible, it is never preferable if there are legitimate ways to avoid it. Their document states that vaccination “is not, as a rule, morally obligatory” and “must be voluntary,” and so goes on to say those who “for reasons of conscience, refuse vaccines” must take alternative measures (masks, etc.) to protect the common good. Apart from the misleading suggestion that prophylactic measures like mask-wearing are of comparable effectiveness with vaccination, such a statement is too easily understood as honoring the conscientious objectors as though they offered a heroic witness to the sanctity of life. As Fr. Matthew P. Schneider, LC, argued in a recent piece published by Patheos, Catholics looking for heroic ways to resist evil have more obvious and much less dangerous options. The pope himself has indicated he is preparing to receive the vaccine, and said in an interview that to do so is “an ethical duty.”

So how should we discuss the morality of appropriation? In my view, the primary question should be about perpetuation. Like many classic cases of cooperation, a moral responsibility to avoid appropriation should recognize that one’s choices can perpetuate—however minimally, remotely, or unintentionally—the evil acts of others. That is, there is a real sense in which one’s action may facilitate an ongoing injustice. Indeed, this concern about perpetuation drives the earlier Vatican instruction Dignitas Personae, which the USCCB document relies on heavily. While the document from the Congregation for the Doctrine of the Faith did discuss cell lines originating from aborted fetal tissue, it’s important to remember that the main context was the intense debate over embryonic stem-cell research in the 2000s. The CDF’s eye was on “cells of illicit origins” because of the considerable pressure to produce and dismember embryos whose stem cells, we were told, would produce countless scientific breakthroughs. The CDF was rightly suspicious of this claim. In the key paragraphs thirty-five and thirty-six, Dignitas Personae condemns all destruction of embryos, as well as the supposedly innocent “material cooperation” that occurs when one “independent” institution creates and destroys the embryos, and then dispenses the “material” to another institution for research.

It is obvious that any activity along these lines would create an ongoing demand for harvested human tissue. And there are real pressures in the scientific world to do experiments and develop products that rely on a steady supply of fetal tissue. Catholics should always stand up against the routine “production” and use of human tissue in experimentation. But these important concerns simply do not apply to the COVID vaccines. Pro-life advocates should focus on the real problems and not get distracted by condemning new life-saving vaccines that have nothing to do with the perpetuation of abortion.

Yet even if the perpetuation of an evil should be the main worry about appropriation, it shouldn’t be the only one. Both the USCCB and their critics raise the traditional concern with “giving scandal.” (Here a brief aside may be in order: whatever the place of scandal in the Catholic moral tradition, the idea of the bishops worrying so much about it right now is pretty hard for many people to understand or stomach.) Having just lived through the Trump presidency, we might now have the perfect stock example of “giving scandal,” together with a reminder of its abiding importance: those who supported Trump “gave scandal” by suggesting that his manifestly objectionable behavior was in fact not objectionable, thereby encouraging others to imitate him.

But it might be better to recall a biblical source of the concern for “scandal” that doesn’t get enough attention: St. Paul’s lengthy discussion of whether new Christians should eat meat sacrificed to idols—that is, the meat many would have had to eat at any distinguished social gathering. At the time, that was an ordinary and urgent practical problem for many converts. The argument in favor of eating the meat was simple enough. Christians know the idols are not real, so why not eat the food? Nevertheless, consuming such meat provoked thunderous accusations of idolatry against those who had thus “compromised.” Paul does not go that route. In fact, he agrees that such meat is not actually “tainted” in any way, but brings up a different consideration. What about the weaker consciences of others, who might be more tempted to believe in idols? He concludes that it is more important to protect the conscience of others than to make use of one’s own rights.

In this way, the concern expressed by the bishops and the CDF about the need to develop procedures and products that do not rely on the fruits of evil is not a matter of excess scrupulosity, but a recognition of what others might infer from such reliance. By using these cell lines without any moral reservations, we risk giving one of two impressions: either that past evils don’t matter or that abortions are not grave evils. Both of these “give scandal,” in the sense of giving encouragement to bad beliefs and behaviors.

But perhaps there is a better way of expressing this idea. In her article, Kaveny talks about the dangers of moral “seepage” and self-deception. We’ve recently seen these dangers on display in Trump-like attitudes among white Americans who think they have no moral responsibility for race relations because “they didn’t own slaves,” or insist that, in today’s world, “race doesn’t matter.” A broader name for this problem might be “desensitization,” especially as it relates to evils we’re tired of hearing about. For all its therapeutic connotations, the term has great value in reminding us of a crucial fact: what becomes familiar to us is less and less able to shock us. I was reminded of this recently when, in a book about American history, I got to the chapters detailing westward expansion after the Civil War. These chapters included many wrenching accounts of the outright slaughter of Native Americans. Did I know that they had been treated brutally and repeatedly pushed off their land? Yes, of course; I had heard the story many times. But stumbling across the historical details of actual massacres made me realize that I’d become desensitized to this massive injustice.

A similar desensitization can and does happen with abortion in Catholic circles. The need to hold our new Catholic president accountable (somewhere other than at the altar rail, perhaps) for supporting increasingly extreme abortion language and policies is something a lot of Catholics would rather not think or talk about. Many Catholics rightly call for a “consistent ethic of life,” but overlook the fact that routine abortion protected by law—not as an exceptional case, but as a basic human right—is such a large-scale contradiction of that ethic. Complaints that other Catholics spend too much time talking about abortion seem to indicate a worrying desensitization to the problem. Just as some people don’t want to hear about slavery or the genocide of Native Americans because, they say, “it all happened a long time ago,” so others don’t want to hear about abortion because, they say, it’s always happened—in every age and place. But abortion remains a grave moral evil, and we should not let ourselves forget that the development of these new vaccines—and an awful lot of other basic science—depend on the taking of a nascent life more than fifty years ago.

In light of all that, should Catholics have any moral qualms about the COVID vaccines? I sympathize with the bishops; it’s hard to answer this question well, because people want to oversimplify it. Two other questions might be better ones. Do the vaccines present any problems traditionally associated with cooperation? I agree with other impeccably pro-life commentators who say there is really no problem with any of the vaccines, since the use of HEK-293 does not involve any perpetuation of abortion. If anyone’s giving scandal here, it’s the pro-lifers who recklessly disregard not only the bishops but also, much more importantly, the great goods to be achieved by widespread vaccination. Associating opposition to abortion with opposition to vaccines on the basis of bad moral reasoning risks leading many to dismiss the whole cause.

And yet one should still ask a second question: Don’t the vaccines somehow bear the stain of individual and social sin? As with so many other things in our society, the answer is definitely yes—and we must guard against any tendency this choice might have to desensitize us to the ongoing injustice of abortion. But the idea that this is the moment for a heroic pro-life witness that will drive HEK-293 out of everyday use seems like an enormous misdirection of moral energy. Instead of arguing over a marginal case of past appropriation, perhaps we can learn something from this that will apply more generally to any appropriation of benefits that derive, however remotely, from evil actions: when it comes to past injustices, we are all sinners. We should never forget this. But neither should we get stuck on undoing past sins in a frenzy of impossible purification. Our most important duty is to act consistently to fight injustice here and now, wherever we find it. When faced with so much past evil, we should wake up every day and first hear the words, “Go, and sin no more.”