Spanish company Nueva Pescanova is close to opening a commercial octopus farm in the Canary Islands. The purpose of this farm is to raise octopuses (and yes, that is an acceptable plural) for food, sparking another round in the debate over the ethics of raising animals for food. This also comes on the heels of the UK adding the octopus to the list of “sentient” animals, garnering for them certain legal protections.  This is a good opportunity to discuss what sentience means and ethics of eating animals.

Consciousness as a phenomenon of living things is a continuum, with things like bacteria, algae, and fungi at one end of the spectrum and humans at the other (humans are objectively the most encephalized or sapient species on Earth). Nowhere along this continuum are there any sharp demarcation lines. Therefore, as humans develop an ethical and moral philosophy for how we should treat each other, the obvious question becomes – to what extent should our ethical philosophy apply to other living things?

First we need to dispense with the extremist position that all life is equally deserving of dignity, respect, autonomy, and all the ethical considerations that flow from these principles. This is an unworkable position, and also does not stand up to close scrutiny. First, all living things exist to some extent in competition with each other. No living thing affords all other living things equal respect. If someone is infected with bacteria, those bacteria may very well kill them (after subjecting them to a horrible illness). Taking antibiotics is mass bacterial murder. Insects are definitely a step up from single-celled creatures, having a primitive neural algorithm that determines their behavior. And sometimes we need to control the population of insects as they try to eat our food, spread infections, destroy our homes, or otherwise be pests.

At the other end of the spectrum there are chimpanzees, our closest cousins, and the other great apes. They clearly have a highly sophisticated central nervous system. They can experience grief, have personalities, can plan ahead, and communicate. Because they are closely related to us, we have an easy time understanding that they are intelligent creatures who deserve to also be treated with dignity and respect. Still, this does not mean the same thing as for humans. Chimpanzees do not deserve the right to vote, or be held criminally accountable for their behavior or enter into a legal contract. While very close to humans, chimps have some obvious limits. There is a solid case to be made, however, that chimps should not be farmed for food or subjected to cruel experiments. They are intelligent sensitive creatures and should not be made to suffer at the hands of humans.

Between chimps and bugs, where do we draw the line? Actually, there can be multiple lines to draw regarding different types of treatment. I don’t like simplistic slogans like, “anything with a face” because it is too vague to apply in the real world (what counts as a “face” and why does that matter?). Rather, I think we should do what the UK recently did – look at all the available scientific evidence to determine how sentient a creature is and then afford them rights and protections accordingly. This is also where the specific definition of “sentient” comes in (in this context, given legal ramifications).

Sentience is defined as the capacity to experience feelings and sensations. Of course, we can never know what it really feels like to be another species. But we can infer it from their behavior and an examination of their nervous system. A mushroom does not have any anatomy that functions in such a way that it can experience its own existence. At most it can react to its environment through basic chemical responses. An octopus, however, does have a complex nervous system. Behaviorally they also engage in complex behavior, seem to have personalities and moods, can problems solve, plan ahead, and learn from prior experience. If they experience pain they will react in the future to the same stimulus as if they remember the pain. From all of this scientists now infer that octopuses are very likely sentient, and should be treated as such.

Sapient is a different standard – the word translates to “wisdom” and refers to creatures that are able to think to such a degree that they should be considered self-aware. Great apes, elephants, and magpies are considered sapient. This again has to be inferred from indirect evidence. One such piece of evidence is the mirror test – can a creature identify themselves in a mirror, or will they consistently mistake their reflection for another creature? Sapient creatures should be treated with the highest level of respect and dignity. This does not mean they should have the same legal status as adult humans. Not all humans have that status, such as children or those with cognitive impairment.

What about sentient but non-sapient creatures? This, I think, is where the main controversy lies. There is a broad consensus that non-sentient creatures like insects should not be afforded individual protections. We can eat, experiment on, and kill them without ethical or legal difficulty. They are, however, collectively treated as part of the environment, and therefore may fall under certain environmental protections. Sapient creatures are thinking feeling creatures who deserve high levels of protection. But in between we have sentient but non-sapient creatures (and even here we have a spectrum), so what about them?

Again, there is a broad consensus that sentient creatures should not be made to suffer. Even when experimented on, they should always be treated humanely.  But that, I think, is where the broad consensus ends and where we get to the nub of the controversy. It is within the scope of humane treatment to keep a mouse in a cage, experiment on it, then sacrifice it at the end of the experiment? Is killing an animal (let’s just assume for a legitimate purpose) inherently inhumane, or can that occur within the scope of humane treatment?

Since we are talking about ethics we can speak in hypotheticals. If a cow is kept in a field where it can go about its cow existence, eating and standing around in a herd, and then one day its existence ends without any anxiety or suffering, is that humane? In other words, is the ethics of eating animal meat determined by the very fact that animals are raised as food, or the manner in which they are raised and slaughtered? Is there ethical meat if the animals do not suffer during any part of the process? This is similar to the question of whether or not it is ethical to experiment on animals, as long as they are treated humanely in the process.

For non-sapient animals, I think there is a strong ethical argument to be made for the position that it is ethical to use animals for experimentation or food as long as they are treated humanely in the process. But I also agree that there is no sharp line here, and I respect different positions that are well-reasoned.