Let us start with three assumptions that almost everyone (especially animal rights activists) agrees on.
First, we value at least one of the following individualistic values (i.e. values that apply to individuals): welfare, well-being, preference satisfaction, autonomy, liberty, health, the right to live, the right to bodily autonomy or the right to property. It is unlikely that you don’t value any of these.
Second, we value justice. This implies everyone has to avoid discrimination based on arbitrary biological characteristics such as species membership. We have to avoid speciesism: the moral status (in terms something we value, such as rights or interests) of all equally sentient beings (humans and sentient non-human animals) is equal.
Third, we value humility. This means that no-one should impose their own values on others, that no-one may prioritize their own weak preferences or valuations above much stronger preferences or valuations of others, that no-one should be arrogant, that no-one should ‘play God’.
Given these three assumptions, we can come to the logical conclusion that ending predation is good and that we are allowed to use safe (harmless) and effective means that reduce predation. In practice, this means we should start with not reintroducing or rehabilitating (rescuing and releasing) predator animals in nature. This effectively reduces predation, because it is not costly for us. In fact, it saves us (in particular zoos, wildlife rescue centers and nature conservation organizations) money and time. Second, we should decrease the meat consumption of carnivorous animals under our care (e.g. cats and dogs). This can be achieved by feeding them more animal-free protein and by developing cultivated meat for predators. Third, and more controversial, we may (or even should, if we could) herbivorize predators.
Herbivorizing predators means turning carnivorous animals into herbivores (or more generally into animals who do not need nor want to kill other animals for survival), by using for example genetic modification (with gene drives) or artificial selection (decreasing the fertility of the more carnivorous individuals in the population and increasing the fertility of the more herbivorous carnivores). Given the fact that some carnivorous species (e.g. giant panda, red panda, spectacled bear, kinkajou,…) spontaneously evolved into herbivores through natural evolution, herbivorizing predators is not impossible and does not go against the laws of nature. Our current knowledge is still too limited, so we can start with scientific research on how to safely and effectively herbivorize predators.
I think the idea of herbivorizing predators is probably the most controversial idea that is related to one of the biggest causes of harm in the world and is the logical conclusion of some of the least controversial assumptions.
How do we come to this controversial conclusion, given the above three assumption? Consider the first assumption: when prey animals are captured and killed by a predator, they lose everything they have and everything they value: their welfare, health, autonomy, freedom, ownership of their own bodies,…
Considering the second assumption, we have to acknowledge that this loss for a prey animal is as bad as a similar loss for an equally sentient human animal. If equally sentient humans are captured and killed by a predator, we would find it horrible. That means the capture and killing of trillions of prey animals is an extreme tragedy. When looking at the victims, we should not make a speciesist distinction between humans and non-human animals. Preying on non-human animals is as bad as preying on humans. But also when looking at the perpetrators who cause the harm, we should not make a speciesist distinction between humans and non-human animals. The immorality of predation cannot be mitigated by making speciesist judgments concerning the cause of the tragedy. Species membership cannot justify the harms done to the prey animals. We should not say that members of one species (e.g. lions) have more rights to harm other sentient beings than members of another species (e.g. humans). For example, the fact that lions do not possess rational-moral agency (are not able to understand morality) does not grant them the privilege to harm others.
With the first two assumptions, we have to conclude that predation is really bad. A world where predators prey on other animals is worse than a world where predation is absent, all else equal.
Now we can add the third assumption: valuing humility. Combined with the second assumption, we have to say that everyone has to be humble. However, by imposing his or her own preferences (e.g. to eat the bodies of others) on many other sentient beings, by capturing and killing those many other sentient beings, a predator is not particularly humble. A predator is arrogant, by heavily interfering in the lives of many others. A predator is ‘playing God’ by determining the fate of many prey animals.
But if everyone has to be humble, this of course also applies to humans. And that is where justifying herbivorizing predators becomes possible. Consider possible objections against such interference with predation.
- Predation is natural and therefore good.
- It is in their nature to prey on animals. We should respect the nature of predators and not change their nature by herbivorizing them.
- We have to respect the integrity of nature, by not interfering with natural processes such as predation.
- Biodiversity not only refers to species diversity, but also to natural process diversity. Predation is a natural process, and by herbivorizing predators we eliminate predation and hence we lose some process biodiversity. Process biodiversity has intrinsic value that we should respect by protecting it.
- We should leave nature alone because human interference violates naturalness, integrity, beauty and pristineness of nature.
- Predators and prey can form a natural equilibrium where prey populations are controlled through predation. We should prefer that natural equilibrium above other ecosystem equilibria that do not contain predation.
All such objections have something in common: they all refer to preferences, values and interpretations of the person who makes the objection. That person has an interpretation of notions such as naturalness, integrity and biodiversity. That person values and prefers those things. But those things are not valued, preferred, experienced or interpreted by nature, ecosystems, predators and prey animals. They don’t care about those values. In contrast, sentient beings such as prey animals care about individualistic values, such as their own well-being, preference satisfaction, freedom and health. They experience and prefer these things.
We can value the naturalness of an animal or the integrity of an ecosystem, but the animal or the ecosystem does not value those things. By valuing naturalness or integrity, we project our own values on animals and ecosystems. In contrast, we can value the welfare of an animal, but besides us, there is always someone else who also values that welfare, namely the animal. That is why valuing animal welfare is not merely a projection of our own values.
So when we decide not to interfere with predation, not to herbivorize predators, because we have some preference for naturalness or integrity, we are basically putting our own preferences, interests or values above very strong preferences, interests and values of others. We are extremely arrogant by claiming that our own interpretations of what is valuable (such as process biodiversity, pristineness or the existence of individuals having a ‘predatory nature’) are better and more important than everything valued by trillions of other individuals (i.e. prey animals). When we decide not to herbivorize predators, we decide that these predators may play God, and that decision means we become the ones who play God.
One could argue that herbivorizing predators violates the autonomy of predators. Herbivorizing could include capturing predators, influencing their fertility,… However, those predators have no valid ground to complain. In general, if an offender violates the autonomy of others (e.g. by capturing and killing them), you are allowed to violate the autonomy of that offender in such a way that the offender cannot reasonably object. This is why imprisoning murderers is permissible. If the offender would object by saying that you are violating his autonomy when you prevent him from violating the autonomy of others, you can say that that is justified because by violating the autonomy of others, the offender implicitly acknowledges that such violations of autonomy are allowed. And because you prevent the autonomy of the victims from being violated, you are doing something that promotes the autonomy of others. The exact same argument goes for imprisoning murderers: that violates their autonomy, but it minimizes autonomy violations, because murderers violate the autonomy of others. Furthermore, herbivorizing someone is a lesser autonomy violation than capturing and killing someone.
If you still believe that we should not violate the autonomy of others such as predators, even if that means others will violate the autonomy of their victims, you should not stop people from herbivorizing predators. After all, stopping those people also counts as an autonomy violating interference. So you have to allow that other people herbivorize predators. Perhaps you think that those people also belong to ‘we’, and hence that they should also not violate the autonomy of the herbivorized predators. But if those people are included in ‘we’, then predators should also be included in ‘we’ (if ‘we’ refers to only humans, it becomes speciesist).
To conclude, consider a thought experiment. Imagine that we find out that our ancestors were once cannibals: they had to kill and eat humans in order to survive. But thousands of years ago, aliens visited planet Earth and decided to genetically modify humans such that they no longer had to eat humans. Would you say that what those aliens did is immoral? Would you say that it is better to be a cannibalistic human? Would you say that you prefer a world where you and all other humans who are currently alive would not exist, and instead cannibalistic humans would exist? Would you say that being cannibalistic is the true nature of humans and that it is bad that the present human generation has lost this true nature due to the genetic modification? Would you say that the loss of this true cannibalistic nature is worse than the loss of billions of human lives who are killed by cannibalistic humans? If you would say such things, you are not humble, but arrogant. You put your own preference for what you consider to be a true cannibalistic nature above the lives of billions of humans.
I think you are glad not to be a cannibal. You do not object against your newly acquired non-cannibalistic true nature, as long as you can eat healthy and delicious food. For the same reason, we can expect that herbivorized predators would not object against being herbivores. And they could not reasonably object, for if they did, they would implicitly acknowledge that we may capture, kill and eat them, and that is something they cannot want.