Harper
Review by Walter Cummins
My approach to The Light Eaters differs from those who have praised the book for its presentation of the latest findings about plant behavior, including the role of what some have designated as consciousness or intelligence. Her data is fascinating, but I’ve been in the midst of a discussion with a friend about whether non-human creatures have consciousness in a human sense. My examples have been cats, animals I’ve observed closely for several decades, not as a scientist but as a food can opener and a lap. The timing of this book about plants has allowed me to stretch my thinking by broadening the range of living things for whom consciousness might apply. That also includes the more basic initial issue of what consciousness means.
One of the primary themes running through The Light Eaters is the scientific community’s dispute about how to classify the new evidence concerning what seems to be plant communication and adaptability. Some are very uncomfortable about calling plant interactions a form of intelligence, this denial going back to the fallacious popular success of a 1973 book called The Secret Life of Plants, which Schlanger considers “a mix of real science, flimsy experiments, and unscientific projections.”
Scientists who knew better were adamant in avoiding the taint of what she calls a collection of myths, even when later experiments confirmed certain abilities of plants to shape their environment. She notes, “Intelligence, applied to plants, did not sit well with plenty of plant scientists, consciousness, an event bolder conjecture, even less well.” They prefer to call what plants were capable of doing the result of “innate programming.” That’s different from cognition or knowing, “at least as those terms are widely understood.”
Schlanger pinpoints an essential issue fundamental to this scientific quarrel that would also apply to any disagreement involving the terms we use to identify concepts and abstractions. She makes a point about the limitations of language in capturing just what is going on with plants when they, say, change the chemistry of their leaves to defeat caterpillars or appear to send messages to all the similar plant species around them, especially “family” members.
“Science indeed has no agreed-upon definition for life, death, intelligence, nor consciousness. … Could plants not hold intelligences that look quite different from our own?” If so, the problem lies not in the evidence of electrical signaling in plants’ equivalent of a nervous system but rather in our linguistic inability to express just what that signaling implies.
Schlanger opens her final chapter with a epigraph from Robert Haas’ poem “The Problem of Describing Trees”: “There are limits to saying, / In language, what the tree did.” Ludwig Wittgenstein is even more extreme: “What can be shown, cannot be said.”
Therefore, the scientific argument may actually come down to the limitations of language, Most people make the assumption that words directly convey something existing in the world instead of just implementing the human verbal code that suggests the actuality of that something. There’s the word and there’s the reality, with the word merely a sound or combination of letters hinting at that reality.
I’m thinking in particular of Ferdinand de Saussure’s theory of linguistic communication and the realization that humans live in a mental realm in which their language refers to concepts that are shadows of the actuality around us, not unlike the shadows of Plato’s cave.
For Saussure language is a system of signs, where each sign consists of a signifier (the sound or written form) and a signified (the concept or meaning). This concept is just a shorthand for what exists in the world. The sign is arbitrary and we ultimately communicate through linguistic conventions that create the illusion of accessing the reality behind them. Schlanger has her own way of making this point: “But words are merely symbols. They draw a perimeter around a feeling for which there is no language.”
Fortunately, in The Light Eaters, Schlanger is able to find the vocabulary to describe how plants interact with each other and with their environment. Some may question how to categorize these behaviors and fit them into an abstract category. For example, they assume the presence of a brain to qualify a living thing for the possession of a form of intelligence. But what if, Schlanger asks, the entire plant is the equivalent of a brain? Would that equal intelligence? Do we have to expand our assumptions about what the word brain refers to?
Schlanger, a science writer who has been spending hours with botanists, understands the equivocation of many in the field, yet she anticipates a change: “I believe we are standing on the precipice of a new understanding of plant life. Science can feel like a monolith; what it says to be true now will always be true. But things can change fast.”
Accepting recent findings that seem to endorse plant consciousness would mean researchers may have brought about one of Thomas H. Kuhn’s scientific paradigm shifts when it comes to the plant studies. Perhaps beyond.
Schlanger senses a larger significance to the outcome of this debate about plant consciousness or intelligence or whatever, the roots of a new paradigm with widespread philosophical implications. Perhaps that shift will include fresh verbal understandings for the signs we use to help us think about living things. “Plants,” she writes, “give us the chance to see the system in which we live.”
