The first Trump administration made it clear that they saw creating fear as a legitimate tool to deter migration. During his campaign, Trump promised mass deportation and there is no reason to think that a kinder, gentler approach will be adopted in his second term in office. But is using fear to deter migration ethical?
It can be argued that it is. Obviously, deterring people by using laws and policies aimed at creating fear is a how society attempts to deter people from committing crimes. If it is morally acceptable to do this to deter potential jay walkers and murderers, then it is acceptable to do this to deter migrants. While some ethicists oppose the use of coercion by fear, the strategy of deterring bad behavior through fear has the approval of Aristotle. This is like the use of force: not all uses of force are to be condemned, just immoral ones. So, the key question is whether using fear to deter migrants is morally acceptable.
In the past, the Trump administration adopted a strategy of creating fear by doing evil. First, the administration aggressively followed a policy of separating children and parents and officials were clear that this was intended to deter migration by creating fear that America would do evil to migrants. It is no accident that in fiction a quick way to show a group is evil is for it to take children from their parents. Second, the Trump administration treated detained children badly. Caging children and denying them necessities is also a stock behavior of evil characters in fiction. This is for good reason since mistreating children is evil. The purpose of this was to deter migrants through fear that if they try to come here, America will put their children into dirty cages without soap or toothbrushes.
Proponents of this policy argued that people choose to come here illegally knowing what will happen, then what is done to them is justified. On the one hand, this has some appeal. If I tell someone that a pot is hot and they grab it anyway, they only have themselves to blame. On the other hand, if people are being pushed into a situation, such tactics mean people will be harmed rather than deterred. Going back to the stove, if I keep a hot pot to deter starving people from taking the food, I will just end up burning hungry people. Saying that they knew they would be burned is not an adequate defense. In the case of migration, many people are fleeing problems the United States helped. People are being pushed by things worse than what the Trump administration tried to do to scare them away.
There is also the fact that, as Locke argued, there are moral limits to how even a criminal can be treated. One of these is proportionality. Separating families and imprisoning children without necessities is a punishment that goes beyond the alleged crime. This is especially important in the case of children; they cannot rightly be considered guilty of a crime and hence punishing them is unwarranted. As such, using these methods is wrong.
As a final point, even if using such wicked means to deter people could be justified on utilitarian grounds, this would require showing that they are effective. However, they clearly did not work, and we were burning the hungry because the pain of the burn is less than the pain of the hunger. The Trump administration was fine with this. While they had hoped these evils would deter people, they had no qualms about doing wrong even when it does not achieve their stated goal. It became evil for evil’s sake, and we should expect more of the same.