The Rational, The Reasonable, and Covid-19 Vaccine Policy

The words ‘rational’ and ‘reasonable’ are often used interchangeably in everyday language. But for philosophers they have specific meanings. These distinct meanings are important because they help to articulate the desirable features of a policy response to Covid-19 and vaccines.

As with anything in philosophy (or any subject, for that matter) there isn’t unanimous agreement on what ‘rational’ and ‘reasonable’ mean but there is enough of a consensus for the claims that follow.


Rationality has to do with primarily with (a) the quality of the inferences one makes and (b) means-ends reasoning (i.e., practical reason). Let’s look at the first aspect of the meaning. Suppose I say that all cats have 4 legs and that Billy is a cat. You conclude that, therefore, Billy has 5 legs. You have made a bad inference and are not rational in that respect. Someone who reasons that Billy has 4 legs is rational since their conclusion follows from the evidence provided.

Similarly, suppose from past experience you know that every time to touch a flame you burn yourself. The next time you see a flame, you touch it because you believe that “this time will be different.” This is as poor inference from the evidence you have collected so far. In that respect, your belief is irrational. To reason that the next flame will be hot is a good inference, and therefore rational.

The second aspect of rationality has to do with what is often referred to as practical reason. Suppose you want to drive from A to B as quickly as possible but you knowingly take the longest route instead of the shortest route (assume both routes are equally accessible to you). This is an irrational decision. The means by which you sought to achieve your goal is not appropriate to the goal.

Given some goal, a rational person (in this respect) selects the most likely means of achieving that goal. When a person acts in ways that frustrate their stated goals, they are irrational in that respect. When they choose the means that is most likely to achieve their stated goals, they are rational.


Suppose you and I are shipwrecked on an island with 10 000 other people. We’re all going to do better if we have some rules that govern what sorts of things are or are not permitted and how we organize our group. Broadly, we can think of these rules as rules of cooperation. If we let everyone do whatever they want, it’s not clear that stable systems of cooperation can emerge. People can make and break rules as it suits them.

Ideally, we want a stable set of rules that so people can have assurances about how others will act toward them and what is or is not permitted/rewarded/discouraged/punished in the group. Stable rules allow for people to make future oriented decisions because they can anticipate how others will behave.

A community–whether a country or a book club–is a system of social cooperation. Stable systems of cooperation require (among other things) agreement on the rules of cooperation. This is true even without the presence of malicious people. People of good faith who must live together can disagree on terms of cooperation and over what sorts of behaviors are or are not appropriate and are or are not beneficial.

Given the fact of human diversity, however, people of good faith will disagree. Anyone who has been a member of any kind of group will have experienced this. So, the starting point for any kind of functioning community is agreement over rules (and a process by which we indicate our agreement). This means that members of the group will propose rules for what is or is not permitted.

Reasonableness, at its heart, has to do with the nature of the rules that one proposes for the group one inhabits. To see this, let’s begin with a clearly unreasonable rule. Suppose I suggest to the group the rule that I spend every day sunning myself on the beach while everyone else works to collect and cook food that I will also eat. This is an unreasonable rule and I am being unreasonable in proposing it.

As Socrates teaches us, it’s not enough to give examples of something to explain what it is. We want to know, what is it about the rule that makes it unreasonable? Here it is. I am proposing a social rule that I wouldn’t accept if the positions were reversed. That is to say, if someone else in our group proposed the rule that everyone else must collect and cook food while they sun themselves on the beach, I would reject that rule if I were on the wrong side of it.

We can capture the notion of reasonableness with the idea of reversibility. As a first pass, this mean that I am reasonable only when I propose rules that I would accept if we reversed positions. The reversibility test is a way of representing fairness. Fairness ensures that the rules that we propose aren’t tainted by our tendency to favor our own interests in our present contingent circumstances. Let’s make like a suitcase and unpack that last part because it’s important.

A central belief that underpins contemporary moral and political theory is that everyone is equal. This does not mean that everyone is equally intelligent, equally beautiful, equally athletically talented, equally tall, equally artistic, equally lovable, etc… This is a statement about moral equality within a political community.

Moral equality consists in the fact that we are all capable of forming and revising our own ideas about what constitutes a good life. Second, we are all morally equal in that we are all equally entitled to pursue and develop ourselves in accord with our private conception of a good life (provided we don’t harm others in doing so). No one is morally superior in this regard. No one within a community has a greater right than another to pursue their own conception of a good life.

The third piece of moral equality concerns access to basic resources that make it possible to pursue one’s own conception of a meaningful life. These usually include some degree of access to education, food, housing, transportation, and medical care. In other words, it’s not enough to say equality consists in everyone being allowed to pursue their conception of a meaningful life. Intrinsic to the idea of a political community is that one must have access to certain basic resources to have a meaningful shot at living a good life. Rights are useless without the resources to meaningfully exercise them.

From the idea of moral equality follows the idea that our contingent material differences–e.g., differences in physical strength, wealth, social status/class, beauty, intelligence, artistic ability, and so on–are irrelevant to the content of the basic rules of society. That is to say, a physically strong person who proposes the rule, “everyone must work except me because I am very strong” violates the precept of moral equality and, therefore, reasonableness. Being a very strong person is not a morally relevant reason for rules that privilege some people’s considerations with greater moral weight than others.

Moral equality requires that (a) every one has the same political rights to pursue and develop themselves according to their conception of a good life and (b) that, in so far as they are available, society provide everyone the basic resources to pursue their conception of a flourishing life. Our natural endowments and social rank are irrelevant to the relative allocation of political rights and basic social resources. In short, just because someone has a lot of wealth or is good at sportball doesn’t entitle them to a greater share basic political rights or basic social resources.

Now we can circle back to reversibility. Reversibility is just another way of representing our moral equality and to convey that our natural endowments or social power are not relevant to basic terms of social cooperation. The basic rules and institutions that order our community must acknowledge each individual’s equal claim to pursing their own personal conception of a good life and that natural talents, social status, and so on don’t give one greater or lesser claim. As fellow citizens we are equal with respect to political rights, access to basic resources, and our say in the rules and institutions that order our community.

Importantly, reasonableness isn’t pure self interest but it isn’t pure altruism either. Reasonableness occupies the space in between the two. It doesn’t require us to completely abandon our personal interests but it does require us to consider the rights and interests of others as having equal weight to our own when setting up the basic rules that structure our political community.

Rationality, Reasonableness and Covid-19 Vaccine Policy

We now have enough background to explore vaccine policy for Covid-19. What elements will a rational and reasonable policy contain? What vaccine policy could everyone endorse regardless of their demographic group, their age group, their access to healthcare, or medical status? Whatever rule we propose, it must be something that both medically vulnerable and healthy people could endorse. Let’s start with what is individually rational.

Suppose you are concerned for your health. You are forced to choose between two states of affairs, A and B. A is a greater risk to your health than B. By the definition of rationality, you should choose B since it is the means by which you best achieve your goal of protecting your health. It is rational to choose the lower risk over the higher risk if we assume the goal of protecting health. This is just the definition of rationality.

With respect to the pandemic we are faced with a very similar situation. Covid-19 is a greater risk to anyone’s health than is the vaccine–regardless of their demographic. We must always think in terms of relative risk. So, if a person’s goal is to protect their health, the rational choice is to get the vaccine since it has a lower relative risk. Choosing the higher risk option while claiming that you seek to protect your health is irrational. It’s the same as choosing to eat 5 large pizzas instead of a salad while claiming your are trying to lose weight.

Now, I know that people have concerns about the vaccine. But as of Jan 14, 11 million people have received the vaccine, none have died because of it, and only a handful have had adverse reactions. Compare that to the reactions of 11 million people getting Covid-19. For any demographic, the case fatality rate for Covid-19 is much higher than 0 and the morbidly and hospitality rates are much higher than for the vaccine. The only way a person claiming to be concerned for their health could choose to get Covid-19 over the vaccine is if they were either irrational or if they misunderstood the relative risks. In other words, they mistakenly believe that the vaccine is a greater risk to their health than Covid-19.

Here’s the thing about a mandatory national or state-wide Covid-19 vaccine policy. You could be completely unreasonable (i.e., not care about other people’s interests or points of view) and still be completely for it since it aligns perfectly with self interest. It’s in my rational self interest to get the vaccine and it’s also in my rational self interest that everyone else get the vaccine (to stop community transmission so we can get back to normal).

A Reasonable Policy: Let’s move on to reasonableness. What we need is a rule that is reversible since, as we now know, reversible rules are fair rules. What vaccine policy rule could someone endorse regardless of their social position or natural attributes? Could the immunocompromised and medically fragile accept the same rule as the super healthy? In fact they can.

What rule would a super healthy person propose to an immunocompromised person and vice versa? The immunocompromised and medically vulnerable person clearly will want others to get the vaccine so they can live a normal life again and not live in constant fear of infection. But is this reversible? Could they accept this rule if they were a healthy person?

As luck would have it, they can. Even for the healthiest demographic, there is less risk associated with the vaccine than there is with getting Covid-19. So, it’s reasonable for the immunocompromised and medically fragile to propose to healthy people that they get vaccinated.

It obviously works the other way too. Given that rational people who want to protect their health will choose whatever policy option best achieves this, healthy people will propose that they and others get vaccinated. They are protected and with other people vaccinated, they are less likely to be exposed to Covid-19.

Could people in robust health could propose that the medically fragile get vaccinated. Is this reversible? As it turns out, barring people with severe allergies and some other rare medical conditions, most medically fragile people are better off getting vaccinated than getting Covid-19. And they are certainly better off if the people around them get vaccinated. Furthermore, as we saw, if healthy people were in the position of the medically vulnerable, they would want the healthy to get vaccinated. The rule is reversible since medically fragile people can accept the rule proposal to get the vaccine if they are medically able. Therefore, the rule is reasonable.

So, there you have it–a policy that is both rational and reasonable: Everyone who is medically able get vaccinated–regardless of their demographic, social position, or natural abilities–ought to get vaccinated. It is both in their self-interest and it is fair.

If you think the policy would be irrational or unreasonable, please let me know why in the comments. I will do my best to respond to you.

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