Interview on Plant Ethics and Intelligence

Easter Island. Photograph by Michael Marder.

 Joe Humphreys Interviews Michael Marder

OCTOBER 22, 2014

A section of this interview was published in The Irish Times on October 21, 2014.
Below is the full version.

JH: You say a plant is an intelligent, social, complex being. What do you base this on?

MM: The first thing we ought to remember is that plants are living beings, and it is a shame that this simple fact is still (or already) not self-evident today. Instead, in our agricultural practices, as much as in the prevailing conception of plants, we treat them as though they were organic machines for producing food, lumber, fuel, and so forth. The situation is very inauspicious, from the ethical point of view, but it holds out an unexpected promise for philosophers, who are quite fond of questioning those presuppositions that silently underpin a “commonsensical” approach to the world.

So, if plants are living beings, then they must be able to interact with the milieu where they grow (including other plants and insects) in order to obtain nourishment and tackle threatening situations. Otherwise, they would not have survived even for a week, let alone for hundreds of millions of years! Their interactions are also bound to be complex because environmental conditions change constantly, requiring an adequate response from one moment to the next.

More than that, since they span diverse environments, from the underground world of minerals and moisture to the aboveground domain that we share with them, plants must be able to keep track of and adjust to countless factors at the same time—from the amount of sunlight to the presence of other plants’ roots in the vicinity. And, indeed, they do! Contemporary plant sciences study, precisely, the different means by which plants can detect what is going on around them, respond accordingly, and share this knowledge.

For instance, they can delay or accelerate their own flowering based on the information they have received from their neighbors through chemical cues emitted by the roots. If, in lab conditions, one plant is exposed to longer hours of light, not only will it blossom faster, but it will also transmit through the roots the news about these favorable circumstances to another plant that does not directly enjoy them. As a result, the recipient of this information will also blossom sooner than expected.[i]

I could amass many more examples such as this, but the point is not merely to regurgitate scientific findings. Rather, I want to liberate the idea of intelligence from its strict connection to the brain, central nervous system, or even animal sentience. I think that plants allow us to do just that—that is, they allow us to reconsider what we mean by intelligence in the absence of recognizable anatomical or physiological structures we tend to associate with the term and to imagine, more broadly, something like “the intelligence of life.”

But there is no scientific evidence to show that plants are sentient beings. Is sentience a requirement for rights?

I wouldn’t be so sure that there is no such evidence. Elsewhere, I have given the example of ethylene, “a classical plant hormone, is one such powerful anesthetic. This hormone, which relieves pain, is released in mechanically stressed plant tissues immediately after wounding.”[ii] Also, if you damage a leaf of a tomato or a tobacco plant, biochemical signals are sent from the site of injury to other parts, warning the rest of the plant about an attack (abiotic stress).[iii]

It turns out that there are different kinds of sensitivity to threat, which sounds the alarm for a threatened living being. In humans and in many animals, pain plays the role of such a forewarning; in plants, distress is expressed in hormonal and other sort of changes that fulfill the same function as pain. Conceptually, we would make the same mistake if we identified pain with sentience as the one where we equate human consciousness with intelligence. Just as there is no life without a minimum of intelligent response to the environment, so there is no vitality without sentience that can and does assume all kinds shapes and forms.

What this implies for ethics is that “sentience as a requirement for rights” is too loose of a prerequisite. As an alternative, we should develop more nuanced approaches, accounting for living beings that, albeit not resembling ourselves, pursue their own interests and ends.

You suggest (if Im not oversimplifying it) that the key moral criterion is to be respectful of plants and their interests. Is it OK to eat plants if you are so respectful?

 With regard to eating plants, it is helpful to know that we can nourish ourselves on some of their parts, such as fruits, without kill the entire organism. In non-Western cultures, this was actually an important criterion for an acceptable diet: Jainism, for example, prohibits the consumption root vegetables, such as carrots or beets, since those parts are believed to house the souls of plants. Westerners can certainly learn a lot about respectful eating from these sources.

Having said that, I think that we put too much emphasis on personal choices in dietary and similar daily practices, while overlooking the fateful decisions on the part of transnational corporations that largely determine what we eat. The corporate commodification of agriculture is particularly disrespectful, in that it sacrifices, among other things, the potentialities of plants and their genetic integrity for the sake of higher profits.

Dietary choices certainly matter, and it would be wonderful if people were to make good decisions that would not be so totally destructive towards animals, plants, and the environment as they are today. But the ethics of individual responsibility is highly overrated in our societies, where respectful diets form small and extremely expensive pockets of resistance to the prevailing agricultural atrocities. There will be no justice or respect toward either plants or animals until agriculture and the economy as a whole are reorganized along non-capitalist lines.

Does your logic extend to meat-eating? Is it the disrespecting of animals, rather than their sentience, which makes it wrong to eat them? 

Imagine that an animal is killed after having been artificially anaesthetized, that is, not experiencing any pain whatsoever. Does such a way of killing it make meat-eating acceptable, having effectively dealt with the problem of sentience? You see, that is why sentience as a criterion is insufficient and the notion of respect is inevitable in any postulation of an ethical diet.

It is OK to bulldoze a forest to make way for a children’s hospital?

Isn’t there plenty of space outside a forest for a children’s hospital and aren’t such medical facilities more needed in populated areas? Many of our so-called moral choices are false not in the sense that we select a wrong option out of the two, but in the sense that they are formulated in terms that are misguided. Plants or animals, a forest or a hospital, and so forth are deceptive either/or choices. Which is why we need a more robust ethics than the one where we engage in complex calculations without reflecting about the pre-given parameters for decision-making.

What can humans learn from plants? 

I have devoted many pages of my books and articles to the idea of learning from plants. If I were to sum up the most vital lesson plants have to teach us in one line, however, it would be: To grow not against but together with the environment, including other human beings, animals, and plants!

What’s the most ethical dish one can eat? 

Eating is not a very ethical activity in and of itself, because, in the process, the eater destroys the independence of whatever is eaten and literally incorporates it into her- or himself. The closest we come to eating ethically is by nourishing ourselves on locally grown fruit or vegetables. As I suggested elsewhere, though, a more significant question is how one eats, rather than what. Does one acknowledge and show respect toward other potentialities of one’s sources of nutrition, resisting the temptation to convert them entirely into food? Does one let a being that provides one with sustenance live? Does one give thanks for this gift of nourishment?





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