Conscience, Virtue, and Moral Concerns about COVID Vaccines

Many Catholics have found their consciences rattled by COVID vaccine mandates and are seeking conscience protections and exemptions. But to champion conscience for its own sake, without appreciating what forms and informs it, is to err on a fundamental level. Any consideration of conscience must be aided by the virtues, those firm dispositions of the soul that enable us to act well in every circumstance—no matter how complex or challenging.

Conscience claims enjoy great prominence in the modern era. For example, in 2020 the Little Sisters of the Poor sought and attained legal exemptions from the Affordable Care Act’s contraception mandate for employers. For Catholics especially, access to such conscience-based exemptions is vital to their ability to freely practice their faith. Recently, many Catholics have found their consciences rattled by another mandate: the COVID vaccines. Their concerns stem from the fact that all currently approved vaccines in the United States were developed or tested using abortion-derived cell lines. However, in obeying one’s conscience, it is vital to make sure that it has been well-formed. How can Catholics ensure that they are being good stewards of their conscience? And how can they think through their moral concerns about the COVID vaccines?

The challenges and controversies surrounding claims of conscience long predate our times. When Thomas Aquinas considers the erring conscience, he affirms that we are bound to follow it—but there is an important catch: if conscience errs because of ignorance that is willful or negligent, we do sin by following our conscience (STh I-II, 19.5–6). If we fail to do our part in forming and informing our conscience, then we may face unfortunate dilemmas: it can become a sin either to follow our conscience, or not to follow it.

To champion conscience for its own sake, without appreciating what forms and informs it, is to err on a fundamental level. Any consideration of conscience must be aided by the virtues, those firm dispositions of the soul that enable us to act well in every circumstance—no matter how complex or challenging. The virtues dispose us both to desire the good and to choose the best means of attaining the good.

The uncomfortable reality is that, without the virtues, there are many ways in which conscience can err. Dominic Prümmer, in his classic Handbook of Moral Theology, considers a number of them: the scrupulous conscience, lax conscience, hardened conscience, perplexed conscience, and—in a nod to Scripture—the pharisaic conscience. So in thinking about COVID vaccines and conscience, we must have an eye to the virtues at all times.


Error and Conscience

If conscience and virtue are both important in the moral life, how are they related? Much ink has been spilled in attempts to answer this. Recent magisterial documents of the Catholic Church—including Pope John Paul II’s encyclical Veritatis splendor and the Catechism of the Catholic Church—have attempted to articulate the precise relationship. Both documents indicate a bidirectional relationship between conscience and virtue. This means that the relationship is not simply a matter of conscience judging something right or wrong and virtue determining how best to act on it. For instance, Veritatis splendor asserts that all the virtues together enable a person to develop his or her good, which is necessary for arriving at “true judgments of conscience.”

Thomas Aquinas’s teachings can help us understand these Church documents on how conscience and virtue interact. According to Aquinas, the term conscience itself “implies the order of knowledge to something,” which in this context means moral knowledge of an individual act. Conscience judges whether an action should or should not be done. To do this, it relies on our innate ability to grasp the basic principles of morality. The foremost of these principles embedded in the mind is to “do good and avoid evil.”

Given this basic understanding of moral principles, conscience judges an act by applying the relevant principles to it. From there, conscience deems that act right or wrong. In this process, our conscience engages in moral reasoning.

By looking at the inner workings of moral reasoning, we can identify steps along the way where error may occur. For Aquinas, our innate moral understanding generates “pure” knowledge, so it does not err; however, the judgments of conscience can err either by incorrectly applying a moral principle to a particular act, or by incorrectly reasoning from premises to conclusion. In other words, people can make mistakes in sizing up the kind of act they are considering, and they can make mistakes in reasoning as they decide what should or should not be done.

The potential for errors of conscience calls attention to the need to form and inform one’s conscience. Because of harmful social influences and personal temptation to sin, education is indispensable for developing an upright conscience. This is a lifelong task that involves continual growth in virtue, which we will consider next.

Virtue and the True Good

The virtuous person acts well out of an abiding state of character. Virtues perfect not only acts performed, but the person doing those acts. Virtuous acts spring readily from dispositions that are formed carefully over time. In complex, demanding situations, the virtues are virtuosic; one might think of a skilled pianist who improvises with great facility. Being virtuous is the very flourishing of our nature.

Virtues can be divided into two broad categories. The moral virtues dispose us to desire the good, and the intellectual virtues dispose us to determine how best to achieve that desired good. One can easily see how these roles complement the work of conscience: the moral virtues make us want to obey our conscience, which enables us to evaluate whether certain actions are good. The intellectual virtues, by contrast, help us to navigate complex situations and act in pursuit of the true good.


Hence, when Veritatis splendor asserts that the virtues are necessary for making “true judgments of conscience,” it means that the virtues support the workings of conscience by avoiding errors. Virtues also help ensure that judgments about the moral quality of acts reflect reality.

One crucial mark of the virtuous person is that he or she recognizes conscience’s limits and seeks counsel from authoritative sources. Desire for counsel is an essential feature of prudence; another is docility, an openness to the advice and teaching of others—especially the wise. These features of practical wisdom bring us out of ourselves and into dialogue, realizing that our understanding always has room to grow.

The rhetoric of conscience tends to have an individualistic flavor. It sometimes implies a fixed judgment without the possibility of or need for further exploration or development. Working together, virtue and conscience reject this caricature and equip individuals to act morally in their communities.

Conscience and COVID Vaccination

Exploring the ethics of COVID vaccination makes significant demands on both conscience and virtue. Broadly speaking, the choice of whether to receive one of the currently approved COVID vaccines involves tension between two grave issues: material cooperation in the evil of past abortions by receiving the vaccine, on the one hand, and promotion of the common good by taking steps to limit the spread of disease, on the other. Added to these concerns are layers of political controversy, as well as the desire to protect conscience rights. Given all these factors, whatever unease people may experience in considering vaccination is likely to involve a complex web of conscience-based judgments.

The problem with relying solely on conscience to navigate this issue is that its judgments are merely the result of a two-dimensional process of reasoning, each time applying a single moral principle to a single act, ultimately concluding whether that act is good or not. Without studied reflection, a person may recognize by the pangs of conscience that COVID vaccination raises serious ethical concerns. However, this awareness may develop no further than a general impression, or perhaps it may narrow to one or two aspects that seem most disconcerting.

For an issue as ethically complex as COVID vaccination, however, conscience by itself is unable to weigh the relevant moral principles, or even to grasp each individual principle with sufficient precision and clarity. How should one weigh the gravity of material cooperation in evil against pursuit of the common good? What is material cooperation in evil? Unaided conscience is ill-equipped to grapple with these questions.

For those seeking guidance on the ethical principles involved, it is helpful to look to sources that predate the current controversy, since the use of vaccines made from abortion-derived cell lines is not new. Dignitas personae, a 2008 instruction from the Congregation for the Doctrine of the Faith (CDF), describes this use as an instance of cooperation in evil and distinguishes degrees of responsibility depending on the level of involvement. For instance, biomedical researchers have a duty to refuse to use such cell lines altogether in their work.

However, those receiving the vaccines are in a different position. A grave health danger might justify their use, “while keeping in mind that everyone has the duty to make known their disagreement and to ask that their healthcare system make other types of vaccines available.” This view is similar to one expressed by the Pontifical Academy for Life in a statement from 2005, which describes such vaccination for reasons of health as an instance of remote, passive material cooperation.


Regarding COVID vaccination specifically, a note from the CDF in 2020 maintains the above teaching and indicates that the otherwise uncontainable spread of a serious pathological agent is a grave enough danger to justify the use of all clinically safe and effective vaccines “in good conscience.” The note counterbalances this by stating that “vaccination is not, as a rule, a moral obligation” and that “it must be voluntary.” However, decisions about whether to receive the vaccine depend not only on the duty to protect one’s own health, but also the duty to pursue the common good. Those who refuse vaccination for reasons of conscience “must do their utmost” to avoid transmitting the infectious agent and endangering the health of others.

Given the ethical principles outlined in the above documents, one question that arises is, what might lead a person to refuse COVID vaccination for reasons of conscience? This complex determination could easily be mixed with errors and requires virtuous reflection. It’s worth remembering that the Catholic Church has long defended conscience rights so that people could be free to follow its teachings, not to oppose what it has already deemed morally licit.

Those considering refusal of vaccination based on concerns about material cooperation in evil should ask themselves these questions: Are there certain circumstances in which I would be more willing to receive a COVID vaccine, or would I oppose it no matter the circumstances? Am I similarly willing to oppose the use of all products that involve the same level of material cooperation in evil? How can I most effectively express my opposition to the development of vaccines developed using abortion-derived cell lines?

Regarding the latter question, it is important and even necessary to express one’s concerns to the pharmaceutical companies that develop or produce vaccines using abortion-derived cell lines, and to advocate vaccines with no connection to abortion. To this end, and in accord with Dignitas personae, the United States Conference of Catholic Bishops has provided on their website sample letters addressed to various pharmaceutical companies expressing these concerns. For anyone who struggles with conscience-based objections to being vaccinated, taking a concrete step like this could help ease one’s conscience and make it easier to thoughtfully reconsider vaccination. In contrast, refusal of vaccination without communicating concerns is unlikely to prompt positive change and may perpetuate misunderstandings.

Because of the importance of conscience, and not in spite of it, it is critical to support the workings of conscience by cultivating virtue—in order to desire the good, eliminate errors, navigate complexity, and determine how best to achieve the good. When conscience and virtue work well together, a person is capable of truly virtuosic action amid society’s increasingly complex challenges.

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