The Real Reason For Interest in Plant Sentience Has Nothing to Do With Plants
I. Plants: They React; They Don’t Respond
Every now and then, the internet lights up with the most recent claim that new evidence indicates that plants are sentient; that is, that they are conscious and have some sort of mind and are relevantly similar to animals.
The evidence on which these claims are based establishes at most that plants are alive and conduct various activities, some of which are very complex. That is, the evidence shows that plants react; it does not show that plants respond. For example, in his 2012 book, What a Plant Knows: A Field Guide to the Senses, Tel Aviv University scientist Daniel Chamovitz wrote that plants could see, smell, and hear. This gave rise to a wealth of claims in the popular media that plants were sentient. But when Scientific American interviewed Chamovitz and asked him point blank, “Would you say, then, that plants ‘think’?” Chamovitz replied, “No, I wouldn’t.” He added, “Just as a plant can’t suffer subjective pain in the absence of a brain, I also don’t think that it thinks.”
Philosopher Michael Marder, author of Plant-Thinking: A Philosophy of Vegetal Life (2103) made headlines when he was credited with claiming that plants are sentient. In a debate that I had with Marder, I asked him whether he thought plants were sentient. He responded that he thought that they were capable of “nonconscious intentionality.” What in the world does that mean? How can one intend to do something in a nonconscious way? Isn’t consciousness necessary for intention? Do plants engage in activities that achieve certain states of affairs? Yes. But it begs the question to talk about “intentionality” in this context. At this very moment, there are all sorts of complex biological processes going on in our bodies. We hope that these processes are conducted toward certain ends, such as cellular repair, and not toward other ends, such as tumor formation. But can we talk about the “intentionality” of cancer cells? Only if we assume that cellular reactions have a cognitive component. We could say that the electrically charged particles that travel down the wire are nonconsciously intending to make the bell sound. But we wouldn’t say that because it would be silly to do so.