In the spring of 1996, my oldest son spent nearly two weeks in a hospital in Kumasi, Ghana. My wife and I had brought him and his older sister to Ghana, where we taught in a seminary for a year. We had left the United States before my son was old enough to receive the MMR vaccine. Unfortunately, though perhaps not surprisingly, in an environment where few people received that vaccine, our risky decision bore ill fruit. Happily, he recovered under the expert care of our Ghanaian family physician, and he suffered no long-term consequences. But things could certainly have turned out much worse.

His non-vaccination was not a result of any moral or religious decision of ours. Nor was his risk from others in Ghana a result of such choices on their part. But these are precisely the sorts of choices being made and defended against the reach of the state today. The right to refuse vaccination is being asserted on the ground of both religious liberty and parental authority.

Religious liberty and parental authority are both important rights. Indeed, they are natural rights. Individuals, societies, and states have an obligation to protect these rights. Still, these rights are not unlimited, nor are they absolute. In this, they are unlike the absolute right every person has not to, say, be enslaved. And so, we must investigate the demands of the common good in order to determine just how far religious liberty and parental authority extend in the case of exemptions from vaccines.

The Reasons to Refuse Vaccination

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A helpful starting point is to evaluate the merit of the reasons for refusing vaccination. If the reasons are strong, and the arguments against vaccination sound, then it can hardly be claimed that the common good requires vaccinations and militates against exemptions.

But the most common arguments against vaccinations, considered on their own terms, are not strong.

To be strong, an argument against vaccination at the personal level must provide some reason for not vaccinating that is proportionate to the risk to one’s children and to others who will be at risk if one’s child becomes sick. This judgment of proportionality must take into account the strength of the reason against vaccinating, the gravity of the evils risked, and the probability of the risked evils coming to pass.

Some of the arguments depend on medical claims about the connection between vaccination and autism that, within the range of my competence, do not seem scientifically defensible. More defensible are the claims that vaccinations do bring some other medical risks. But those risks are very small, smaller than the risks accepted for many other goods, such as the risks involved in driving a car with children in it.

Of course, there is no push to make driving your car mandatory, and some people understandably resist the imposition on freedom involved in any mandatory undertaking. But, in itself, resistance to the exercise of authority is unreasonable unless the authority is itself being unreasonable or one has other good reasons to resist. I will return to the reasonableness of this exercise of authority below.

Aborted Fetal Cell Lines and Cooperation with Evil

What about religiously based reasons for refusing to vaccinate one’s children? While some Orthodox Jews are known for their vocal opposition to vaccines, Jewish law does not prohibit them (even when the vaccine contains gelatin from pig tissue), and much of the opposition seems rooted in the concerns just discussed.

Some Catholic and other Christian parents point to the origin of important vaccines in cell lines derived from aborted human beings. Both MRC-5 and WI-38 cells, for example, are used in the production of the MMR vaccine, and both are derived from children aborted in the 1960s. The vaccine itself, however, contains no cells from the aborted children.

Here, the main concern is likely to be one of cooperation. Cooperation takes place when an agent does something that will in some way be of aid to some other party who performs evil acts. Such cooperation can be formal (when the cooperator shares some or all of the intention of the evildoer) or material (when the cooperator’s intention does not at all overlap the evildoer’s intention).

Formal cooperation with evil is always wrong, but material cooperation can be permissible when the reasons for acting are proportionate to the reasons against so acting. This requires consideration of the goods and ills that will result from the cooperating act. For example, one of the possible effects of material cooperation is on the character of the cooperator, who can become habituated to the action in question, finding it easier and easier. He might eventually come to endorse the wrongdoing, thus becoming a formal cooperator. Another possible effect involves how the cooperator’s involvement is understood by the wrongdoer, or by other third parties.

The assessment of proportionality in material cooperation is a vexed issue, but the main point to make here is that vaccination does not entail either material or formal cooperation with the earlier abortions used to procure the MRC-5 or WI-38 cells, for there is no cooperation with those abortions at all. The wrongful acts at issue were performed decades ago, and it is not part of a recurring pattern or project. The actions of the wrongdoers are beyond our reach, and so there simply is no possibility of cooperation of any sort.

More could be said on this topic, of course, but with regard to vaccines that use cells from these, or similar, lines, the most plausible objection to them, that they constitute impermissible cooperation, is based on an error.

The Reasons for Mandatory Vaccination

So the reasons against vaccination seem weak. But the reasons for vaccination, as I know from experience, are strong, including health benefits both for the vaccinated person and for other unvaccinated persons through herd immunity. Vaccines such as the MMR were, indeed, greatly lauded when invented, for they were viewed as a major advance in the promotion of health and life, a complex and basic human good. The first twenty years of use of the measles vaccine in the United States, for example, is estimated to have prevented over 50 million cases of measles, and over 5000 measles-related deaths.

Thus, the argument for vaccinating one’s children seems quite strong. Accordingly, the National Catholic Bioethics Center argues that parents with a properly formed conscience will assent to vaccination for their children.

In itself, of course, that does not mean that it is reasonable for the state to make vaccinations mandatory, nor that it is reasonable for the state to refuse to accommodate those who still have religious objections.

As to the first, it is entirely reasonable for the state—in the US context, individual states—to make vaccinations mandatory for children attending public schools. Such laws are common in US states, and they serve to realize important health-related goods that might be jeopardized by negligence, lack of care, and other predictable failures of parents to fulfill obligations that they already have. Legally mandating vaccines ensures a higher rate of compliance than could otherwise be expected among people who for the most part have few objections to the practice. And the risk of an increased infection rate rises when many children spend a large part of their day together in close quarters.

The Limits of Religious Liberty and Parental Rights

But, of course, there will always be parents who object to mandatory vaccination laws. Even if these parents are in objective error, neither religious liberty nor parental authority is predicated on those rights being exercised in the most fully reasonable way. Persons in the grip of religious error still have rights to believe and act in accordance with their sincere religious beliefs. Parents who make good-faith errors—and even somewhat negligent or irresponsible parents—still have a rightful authority over their children, grounded on their obligations to care for the human beings they are biologically and socially responsible for. Neither religious liberty nor parental authority can simply be ignored or easily trumped at the whim of the state.

Yet neither right is absolute. What the Second Vatican Council said of religious liberty also goes for parental authority:

This Vatican Council declares that the human person has a right to religious freedom. This freedom means that all men are to be immune from coercion on the part of individuals or of social groups and of any human power, in such wise that no one is to be forced to act in a manner contrary to his own beliefs, whether privately or publicly, whether alone or in association with others, within due limits.

“Within due limits”: there is the rub. We should understand this expression as pointing to the demands of the common good—not an imaginary “greatest good,” but instead the set of conditions that make possible the pursuit of human fulfillment by human persons, acting individually and in community with others.

When that common good is jeopardized by the religious or parenting choices of individuals or groups, then the default against state interference with religious liberty or parental authority begins to wane. This is true when, for example, the religious liberty of some person or persons is exercised in a way that jeopardizes the lives and health of others. It is likewise true when parental choices jeopardize the life or health of children.

There are times and places when the life and health of children and other unvaccinated persons is not greatly jeopardized by granting accommodations to parents with religious objections to vaccination, even if those objections are objectively unsound. Where both parenting and religious exercise are concerned, there should be a presumption of freedom, and there is little to be gained, and much to be lost, by coercing people simply on the grounds that their position is in error.

But by the same token, when the circumstances are such that the risk to children and others grows, the presumption is rightly overcome. Widespread risk of measles is in fact a significant threat to health and even life; and those at greatest risk, including unborn children, are not making their own choices. It is thus reasonable for the state to act on their behalf to protect them from the choices of others. Such protection also honors the presumption of freedom by protecting those whose freedom is put at risk by other persons’ choices.

In the United States in 2019, there have so far been over 1000 cases of measles, the highest number since 1992. While that is far from an epidemic, it is nevertheless concerning for a highly contagious disease. Different states will make different judgments about when precisely the scales have been tipped in favor of restricting or eliminating exemptions to mandatory vaccinations on religious or even philosophic grounds. But it is a mark of responsible governance, not authoritarian overreach, for states to act when the demands of public health seem reasonably to call for such measures. It is true that the presumption of freedom, religious liberty, and parental authority are all at risk in various ways in an increasingly regulatory, secular, and statist culture, but it is an error to see vaccination policy as an essential battleground for defense of these important rights.