What Would Plant Sentience Mean for Vegan Ethics?

Late last year, there were a couple of popular articles looking at the surprisingly intricate ways that plants interact with their environments, Michael Pollan’s “The Intelligent Plant” and Kat McGowan’s “The Secret Language of Plants.“ More recent (and brief) was Becky Ferreira’s “Plants Are Capable of Making Complex Decisions.” None of these articles claim that plants certainly feel pain or have conscious “interests,” but they all suggest there is still far more to plants than we realize.

Some people interested in food ethics (or at least the food ethics debate) think that if science declared plants to have a form of sentience, this would complicate things for vegans without much inconveniencing omnivores. “What about plants?” is a question that meat eaters often throw at vegans in this spirit, as if the fact that plants are alive means it’s silly to consider the interests of the animals we eat. Vegans break down the categories separating humans from other animals in a way that makes meat eaters uncomfortable, so in revenge meat eaters break down the categories separating non-human animals from plants to try to make vegans feel the same kind of discomfort. It’s a shot at beating vegans at their own game.

Essentially, “what about plants?” attempts to discredit sentience as a guide to our ethical decisions by implying that if we respect all sentient creatures, everything we do is unethical. The problem is that the “what about plants?” argument typically equivocates between “sentient” and “alive/responsive” and offers no real proof that plants are sentient.

The animal farmer Joel Salatin was a case in point during last year’s Intelligence Squared debate about the ethics of eating animals:

And, you know, I find it fascinating that all of the attributes given to animals plants have too. The DNA structure of grasses, for example, when you introduce a species, it nativizes its DNA structure to become more climatically nativized to a certain place. That’s memory. That’s genetic memory and adaptation to a certain place. If that isn’t responding to things, I don’t know what is. And I just absolutely don’t appreciate this false dichotomy that when I take the life of a carrot, the carrot doesn’t scream.

This is about as weak as the “what about plants?” argument gets because it utterly fails to anticipate the vegan response that plants don’t feel pain and don’t have conscious interests. With no reference to sentience, Salatin is taking for granted that genetic sophistication is significant in itself, but makes no allowances for degrees of genetic sophistication and so is essentially saying, “Anything that’s alive is all the same.”

Meat eaters who use this argument are typically attacking vegans on two contradictory fronts. On the one hand they say that humans and animals are different, and these differences explain why meat eating is okay. Then with “what about plants?” they do the opposite, linking all of creation together — "All-One!” as Dr. Bronner would say. Unfortunately, by dismissing the distinction between killing plants and killing non-human animals for food by linking them together through aliveness, they also erase the distinction between killing plants and killing humans. ￼

If you think that “what about plants?” means there is no difference between exploiting animals and plants for food, then you’d have to say the same about exploiting humans for food, because you’re denying that there are different levels of aliveness, or at least denying that these different levels could justify different treatments or considerations. To turn around and admit that there’s a difference between killing plants and killing humans in light of this is to grant that there could also be a difference between killing plants and killing non-human animals. The whole argument just renders itself moot.

But let’s pretend for a moment that “What about plants?” is really onto something. What would it mean for food ethics if it turned out that plants do in fact have a form of sentience that was comparable to the sentience of some animals?

This probably wouldn’t be a huge issue for meat eaters, who don’t tend to care much about sentience per se when they’re deciding what to eat. The sentience of non-human animals didn’t stop them, so why would the sentience of plants give them pause? Conscientious omnivores might want assurance that any sentient plants they eat were treated well, given a natural diet of sunlight, fresh water and organic manure, and were killed quickly and painlessly, but there would be no qualms about the killing of plants in itself. For vegans it would have potential to be more of a problem because plants would suddenly fit the bill of what they consider to be unethical to eat. Never eating again would be one possible solution, but probably not one most vegans would want to embrace.

Another option would be for vegans to confess to having a more emotional form of ethics than they sometimes let on, admitting that it’s not violating interests that’s the problem, but violating interests in a more blatant and viscerally disturbing way. Even if plants were sentient, it still wouldn’t look horrific to pull them out of the ground; in comparison, shooting a bolt through a cow’s brain looks pretty gruesome. Vegans could say that’s the key — not that one violates interests and one doesn’t (plant sentience makes that dichotomy impossible), but that one violates interests in a manner that is more emotionally upsetting to vegans. Even if animals were unfeeling automatons (which obviously isn’t the case) there could still be a quasi ethical argument for veganism, which would be that the aesthetics of animal exploitation and slaughter disturbed a lot of people, or that animal slaughter is a dangerous and desensitizing job for humans because of the visual similarity between killing humans and non-human animals.

But this would be a major compromise for any vegans who like to think they argue mostly from logic, so I don’t think many vegans would settle for it.

The stock vegan response to the possibility of plant sentience is to appeal to suffering reduction: “Well, vegans kill fewer plants than omnivores anyway because the animals you eat were fed plants.” But that’s only true when we eat farmed animals. Someone who eats only animals that they hunt is seemingly responsible for fewer plant deaths than vegans, especially if they hunt herbivores. So if plants were sentient and had lives worth living, a hunting-based carnivorous diet would perhaps be the most ethical until we ran out of non-human herbivores to kill. At that point, humans with vegan ethics would again be in the position of having to think of their very lives as inherently unethical, coming as they do at the expense of sentient plants. In-vitro meat would no longer be enough. In a world with sentient plants, vegans would need to develop in-vitro vegetables: lab-cultured plant-like foods, made from non-sentient material.

But this assumes no gradations of sentience and interests. Even if plants were sentient, would this automatically require that vegans try to grant them the same ethical consideration that they want to grant pigs or whales? That depends on the vegan: some acknowledge degrees of sentience and some don’t. In the former group is vegan RD Jack Norris, who sometimes encourages non-vegans to eat insects:

A move from people eating mammals and birds to crickets is something I can get behind. … I follow this hierarchy of valuing animal lives differently in my everyday actions. For example, if I were to see an injured dog, raccoon, or bird on the side of the road, I would stop and try to get the animal to a veterinarian. I will not do this for injured insects. In fact, if I thought insects’ lives were as valuable as mammals, I wouldn’t drive at all because it’s inevitable that I will kill insects with my car just about any time I drive (at least during warmer months). If I knew that I would kill a mouse or a chicken every time I drove my car, I wouldn’t do it. … From a scientific perspective, I think there is evidence that insects do not have enough brain tissue to assume that they have a self-identity and can be aware of suffering. I might be wrong about this and if so, I definitely need to reconsider my driving habits… [W]hen it comes between a mammal and an insect, I’d side with the creatures that we have a large amount of proof for being conscious.

A veganism that allows this more permissive attitude about eating insects and brainless sea animals would basically be immune from the additional challenges that sentient plants would pose for the philosophy, so this would probably become a more popular stance in the wake of a plant sentience bombshell. If you accept degrees of sentience, it becomes plausible to see a difference between exploiting brainless sentient plants and sentient pigs. Where you draw the line becomes somewhat more arbitrary, perhaps, and you couldn’t exclude all animal products from veganism any more, but you could still make a case for protecting farm animals without extending the same consideration to farm plants. The more difficult issue for these vegans, I think, would still be all the wild animals that a vegan world would routinely harm and kill.

The sentience of plants would however pose a special difficulty for the deontological breed of vegan ethics in that it would become all the more ludicrous to appeal to “intent” and to play up the ethical differences between the accidental or indirect killing of sentient beings versus the intentional and purposeful killing of sentient beings. By eating sentient plants, vegans would be intentionally killing sentient beings for food, so the idea of their granting rights based on sentience would be in shambles. “Hey, we have to eat something!” would be the argument of last resort, which immediately fails because no, we technically do not. There is no obligation for humanity to survive, and so if we go on while knowing that we must violate the interests of non-human sentient beings to do so (both plants and animals in this hypothetical), we can’t plausibly claim to be respecting the rights of non-humans.

That’s why I think another significant change would be a greater shift away from deontological arguments for animal rights toward the utilitarian and utilitarian-esque suffering reduction perspective. (Or maybe eco feminism, or other alternatives like obfuscating continental-style philosophizing.) What distinguishes vegans from omnivores in this scenario is a goal of hurting others less, so it could make ethical sense to eat plants, insects and bivalves — even assuming all are sentient — if this causes less harm than eating farmed animals.

Where this would get really complicated is with utilitarian perspectives that are very concerned with suffering on the aggregate. Here we find utilitarians who think that insect suffering might be one of the world’s most pressing concerns, because there are so many of them and they reproduce and die so quickly, which means that their experiencing even tiny amounts of harm on an individual level adds up to vast amounts of suffering. Utilitarian philosopher Brian Tomasik discussed this in my interview with him. If plants were as sentient as insects, and if we decided to aggregate plant suffering too, it would no longer be so clear that plants and insects were the right things to eat. (Perhaps it would be better to try to make plants go extinct and to eat larger beings like whales, for instance.)

Plus with all this extra suffering to contemplate, life could be seen as an inexcusable nightmare, an unfathomable sea of suffering that can’t dry up soon enough. This could make vegans feel more of a need to align with radical negative utilitarianism, perhaps lobbying for the end of all life. Or it could inspire vegans to stick with a vague utilitarian-esque approach of wanting to reduce suffering, but without aggregating that suffering, so as to avoid thinking too much of all the suffering there is in the world. That would be fine, but it still wouldn’t allow vegans to convincingly propose many solid rules about what was okay to eat.

So basically, vegans should really hope that we never figure out that plants are sentient. This doesn’t mean that impressive new discoveries of plant intelligence are anything for meat eaters to celebrate. If plants are far more brilliant and sophisticated than they seem, might not the same be true for non-human animals?