Put simply, risk is exposure to a danger with some probability of occurring. Of course, seemingly simple concepts are rarely simple in practice. Because we encounter such a wide range of risks throughout our lives there is no way to consider them all.
The majority of risks most of us are exposed to day-to-day come from the fact that we interact with other people. Neighbors, other drivers, food processors, engineers, electricians, chefs, car assemblers, pilots, etc., are just some of those who take actions that could put us at risk. A mistake at the wrong moment by one of the countless people we rely on could injure us, cause major property damage, or even result in our death. So when does exposing another person to risk without their consent rise to the level of an aggression? (An “aggression” being an action such that the person subjected to it can legitimately use physical defensive force to repel it, and may also be due compensation.)
Before tackling that question, we need clarity around exactly who can (and cannot) commit aggressions in the first place. Risks from natural phenomena can’t be considered aggressions, as they are not purposeful human action. Also, libertarians recognize that collectives cannot act. Groups are not themselves single-minded entities, so a group of people as a whole cannot commit aggressions (only each individual within the group). Therefore, only individual people can impose a risk that could elevate to an act of aggression.
The two major components that determine whether an imposed risk can be considered an aggression are the intent behind creating the risk and the severity of the risk. Unintentional situations that put others at risk may not be aggressions unless the person causing the risk was willfully negligent, or otherwise should have known what they were doing.
When an action that imposes a risk without consent is purposeful, we must then consider the severity. An airline company creates a new route where planes are now going over your home at 35,000 feet. You are now subject to a risk you never agreed to accept. Yet few would support your decision to approach the pilots of those airplanes and use “defensive force” to get them to stop the flights. On the other end of the spectrum, someone who shoots at you is creating a significant risk of your injury or death. Such an act is clearly one that allows for physical force to defend against. Therefore, at some point in between these two extremes is the “line.” The point at which risks stop being just part of life, and start being criminal acts.
Unfortunately, that line cannot be objectively defined. It will be different from person to person, location to location, and culture to culture. The particular risk that has been in the news since February 2020 bears this out. Many people are deeply divided not only on the severity of the risk, but also on the methods by which it should be mitigated.
Arguments made to support defensive action in order to reduce the risk of spreading a virus are fundamentally flawed. A common comparison is that of drunk driving. The argument (steel-manned from the minarchist/libertarian perspective) goes, “A person who is putting others at additional risk without their consent by driving drunk is committing an aggression. That aggression constitutes a legitimate use of defensive force to remove the person from the road.” The non-libertarian may add, “We as a society have decided this through our representatives who wrote laws against drunk driving.”
This comparison leads to the assertion that since the risk of dying in a pandemic is higher than that of drunk driving, and “we as a society” have “accepted” the use of force against drunk drivers specifically because of the additional risk they impose, and because it is other people’s actions (e.g., not wearing a mask, not getting vaccinated, or refusing to show proof of it) are what generates the elevated risk to others, that it is justified to use force against those who could potentially infect others just as we do drunk drivers.
The principled libertarian will see every mistake in the above position. We can start with the inconvenient point that over an 11-year period, six times as many people on average have died from influenza each year than of drunk driving, yet there were no calls to criminalize the flu. (Even the act of knowingly having the flu and bringing it to work or school has never been widely discussed as being an aggression — even in the midst of the current situation. I welcome evidence to the contrary.)
Set aside the idea that “we as a society” can ever “decide” or “accept” anything. Also set aside the question of whether the politicians who created drunk driving “laws” did it for “our” interest, or because of political calculation. We only need to examine the steps necessary to determine criminality to show that using drunk driving as a comparison to walking through the store with no mask should be rejected.
When a person is driving, the only outward indication they are impaired is their physical actions — weaving in the lane, slowing and speeding, etc. It can be reasonably argued that those signs indicate that the particular individual in question is creating a risk. Without these visible signs there is no justification to suspect a person is violating the law. Yet with a virus, any human being — symptoms or no symptoms — can be a “potential” carrier which is why it is argued that every human must partake in risk-reduction activity: wear a mask and get vaccinated. (And, because vaccinations are not outwardly visible like masks, proof of vaccination must be presented.) If no particular person can be identified as creating a risk, and there is no visible evidence that any person is acting to create a risk (i.e., not symptomatic), then it cannot be presumed that everyone is a risk. Force cannot be used against any individual to mitigate a risk they are not clearly creating. This would be like every driver being stopped and tested for alcohol consumption even when they were driving perfectly.
This should be the end of the argument. There is no limit to the tyranny that can be wielded if force is used against people for their “potential” for harm. Reasonable people can discuss the amount of risk a person is imposing on others when there is an identifiable individual exhibiting specific evidence of doing so. But a general use of force against masses of people with no evidence of specific wrongdoing is itself a crime that comes with a legitimate moral option to use defensive force to repel.