Is it possible for any form of animal consumption to be consistent with the moral concerns of ethical veganism and vegetarianism?

Consider the oyster, a member of the class of organisms known as bivalves, marine and freshwater mollusks that have bodies compressed between a hinged, two-part shell. This group includes clams, scallops, oysters and mussels. Bivalves, which fulfill a more and more significant role in the American diet, are the source of significant controversy among animal product-avoiders, as their consumption raises new questions about the value of descriptive consistency in vegetarianism and veganism.

Ethical eating isn’t about having lots of rules or an annoying diet. It’s about choosing not to make animals suffer and not to damage the earth. So, meat-eaters and pescatarians nervous about taking the plunge into vegetarianism and veganism should realize that the choice to eat more ethically may not be as difficult as they had believed, especially if they are fans of shellfish.

Often, we condemn eating animals because doing so causes a tremendous amount of suffering and is (usually) antithetical to environmental stewardship. But what if there was an animal that thrived under factory farm conditions, cleaned up its environment merely by existing and was indifferent to its own slaughter? That describes the life of the farmed oyster. So, can we make the case, as ethical consumers, for their consumption?

Philosopher Jeremy Bentham famously said, “the question is not, Can they reason? nor, Can they talk? but, Can they suffer?” This oft-touted line is the scaffold of moral reasoning for many forms of ethical veganism and vegetarianism. Bivalves, much like plants, may not have the capacity to suffer. Unlike pigs, chickens and even lobsters, they have no central nervous system, not even a concentrated processor for stimuli. As evolutionary psychologist Dr. Diana Fleischman describes in her blog on sentience, although bivalves can respond to stimuli, “there is no place for sensations to be aggregated into responses or changes in adaptive decision making.” In other words, they’re more like especially fast plants than other animals; they react, but there’s no internal experience.

But the capacity to suffer is not the only motivation for the choices made by vegetarians and vegans. Producing and eating animals is usually very inefficient and environmentally degradatory. But, bivalves (and especially oysters) seem to avoid this pitfall as well. Oysters are adept at filtering out noxious particles in the water, so much so that they are often used to clean up especially dirty bodies of water. When farmed, which accounts for 95 percent of all oyster production, the process is actually beneficial.

In fact, there are now nonprofits that farm oysters as a means of environmental remediation—improving water quality and providing “structure and habitat needed for many other species to survive” in bays throughout New York and New Jersey. Filter feeding is simply part of the natural life cycle of many bivalves and in no way makes them unfit for consumption.

Because oysters are usually farmed by tank-based cultivation and transplantation, there is little risk of overfishing. And they’re comparatively efficient: There is no call for massive amounts of grain to be produced, no need for forests to be razed, no pesticides are required and, perhaps most importantly, “oyster farms operate without the collateral damage of accidentally killing other animals during harvesting.”

Although bivalves are technically animals and thus eating them isn’t strictly vegan or vegetarian, eating bivalves still seems to satisfy many of the moral prerequisites involved in ethical consumption. If bivalves, like plants, are truly non-sentient, their avoidance is simply a mental exercise of empathy rather than a real moral obligation. Certainly, we do not in the least mean to criticize those who choose not eat them, but simply stress that there appears to be no ethical difference between snacking on an oyster and a carrot.

It should be noted, however, that many vegetarians promote avoiding all dead animal consumption because it’s an easy idea to wrap one’s head around, makes a spreadable meme and is a good proxy for  what’s needed to reduce animal suffering as much as possible, even if it causes people to reject a few unobjectionable items. This is even more true of vegans. It’s partly about building a community and an identity. If weird exceptions like oysters complicate that, it may not be worth eating them at all. However, this may not be the case. In fact, explaining what makes it okay to eat bivalves may highlight the moral horrors of other animal product consumption, rather than obscuring them.

Vegetarians and vegans correctly state that moral distinctions based only on taxonomy (i.e. the idea that it’s okay to cause an animal suffering just because the animal is not a human) are faulty. Like other moral distinctions based on morally irrelevant qualities like religion, race, sexual orientation and nationality (and many more), taxonomy-based distinctions allow nearly unimaginable horrors to be inflicted. We must be deeply suspicious of our tendency to let morally irrelevant differences guide moral actions, as history has shown that people have made this mistake, unceasingly, over and over again.

Most vegetarians and vegans eat plants not because they happen to belong to the Kingdom Plantae, but because eating them inflicts less suffering and environmental damage than eating meat and most other animal products. Similarly, we should not avoid eating bivalves simply because they are animals, but instead evaluate them in the morally relevant manner—by looking at whether they can suffer and whether their consumption contributes to our planet’s degradation. If we do so, the ethical consumer should feel no shame in eating the occasional oyster.

Contact Claire Zabel at czabel ‘at’ stanford.edu and Joseph (Joey) Zabel at joezabel ‘at’ stanford.edu.