Michael Marder: Do plants have their own form of consciousness?

“At the moment, our political and ethical thinking about vegetation is lagging behind these discoveries. Most people consider plants to be bordering on machines, wholly determined by external factors. And nothing is more conducive to the deepening global environmental crisis than the complacent and un-problematised equation of trees with raw materials – available for unlimited human consumption.” — Michael Marder

On Sunday, Al Jazeera English published “Do plants have their own form of consciousness?,” an opinion article by Michael Marder, Ikerbasque Research Professor of Philosophy at the University of the Basque Country and author of the forthcoming Plant Thinking: A Philosophy of Vegetal Life. In his article, Marder discusses the controversy stirred up by his two New York Times articles, reflects on his debate with Professor Gary Francione (originally hosted here on the CUP Blog!), and provides further evidence for why we should care about plant thought.

Marder is concerned about the way that political and ethical thinking about plants is failing to change as new scientific information about plants is discovered:

It seems, however, that all this is but the tip of an iceberg now emerging from the stagnant waters of humanist ethics. Even a cursory consultation with the findings of contemporary botany is enough to gauge how research is rapidly dismantling what we thought we knew about plants. Not only can some plants defend themselves by releasing volatile chemicals that attract the predators of the very herbivores who feed on them but they can also differentiate between members of the same species and “strangers”, altering their root growth in response to the identity of the neighbouring plant.

At the moment, our political and ethical thinking about vegetation is lagging behind these discoveries. Most people consider plants to be bordering on machines, wholly determined by external factors. And nothing is more conducive to the deepening global environmental crisis than the complacent and un-problematised equation of trees with raw materials – available for unlimited human consumption.

Marder is concerned about the way that 19th century attitudes about plants predominate popular and academic discourse about dietary and agricultural ethics. He believes that having discussions about these important topics without allowing prejudice to dictate our positions is our immediate challenge:

The challenge is to initiate a dialogue between the scientific and the philosophical issues related to plant life, without allowing prejudice to creep into either. In this respect, the fundamental philosophical questions here are: How are we to think through the foundations for ethical thought and action? And is this foundationalist approach still justifiable, relevant or useful? Are we to treat ethically only those living beings that most resemble us, ie: sentient animals? Is empathy the ultimate basis for determining how to treat someone or something? Or, is an ethics of difference (or otherness) needed so as to account for our conduct toward life forms that do not facilitate our sympathetic self-recognition?

I believe that this last point is especially relevant to the ethics of plant life. Although plants might not have the capacity to experience pain, they relate to the world in ways often drastically divergent from those employed by humans or animals. Let us take the example of language. It would have been fair to say that, in talking about “plant communication”, we merely project our own realities onto plants, if (and only if) communication were a uniquely anthropomorphic phenomenon.

But why, asks Marder, should we care about plants when humans and animals are suffering, given that plants are not sentient? This question, he claims, is no different than asking why we should care about animals when humans are suffering, given that animals are not rational.

Compared with the horrific abuse of animals, which undoubtedly intensified with the industrialisation of agriculture, our comportment toward plants is less disturbing because, after all, a felled tree does not scream in pain as a slaughtered pig does. But this does not mean that the ongoing exploitation of plant life ought to be condoned.

To call attention to the need for justifying our otherwise unbridled instrumentalisation of vegetation is not to argue that animals should continue to suffer in industrial farm settings and slaughterhouses as well. This is a non sequitur – a conclusion that does not follow from the preceding premise and an appalling piece of fallacious thinking. Those who think that drawing attention to the unlimited violence perpetrated against plants is a distraction from their concern for animals are the unfortunate victims of this crude fallacy.

Marder concludes his article by claiming that “we should interpret the results of current plant intelligence studies in botany as a wake-up call to philosophers.” He believes that the fields involved in the study of the mind in particular need to take note of developments in “plant thinking”:

The other source of anxiety lies hidden in the responses of neuroscientists, who have long reduced human consciousness to a series of cellular and molecular interactions. Plants, of course, do not have a central nervous system but this does not prevent them from sending complex bio-chemical messages, for instance, through their roots and altering their growth patterns as a result.

Evidence for the non-metaphorical memory of light residing in plant leaves adds insult to the injury suffered by the argument of those who still insist on the exceptionalism of the central nervous system. In other words, when consciousness is wholly embedded in its biochemical substratum, it becomes increasingly indistinguishable from the cellular and molecular processes of other, presumably nonconscious organisms, such as plants. The freedom (or plasticity) of plants is the obverse of the deterministic stricture, into which neuroscience has forced the grounds for human conduct.