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Machines Like Us

Peas and quiet

Sunday, 13 May 2012
by Leonard Finkleman

Dateline: 1968. Cleve Backster, inventor of the polygraph, attaches lie detectors to some house plants and proceeds to yell at them. When his polygraphs register responses from the plants, Backster publishes a paper in the International Journal of Parapsychology (second only to “Weekly World News” in its academic rigor, I’d imagine) declaring that plants have perceptions and feelings. Thus do I have to waste at least fifteen minutes each semester explaining to students why plants don’t factor into utilitarian calculations. Thanks, Cleve.

Forty-four years later, the New York Times publishes an essay by philosopher Michael Marder in its “Stone” opinion column wherein the author insinuates that peas can ‘talk.’ Wonderful: there goes another fifteen minutes out of my virtue ethics lecture (1).

In the decade following its publication, Backster’s research into plant “primary perception” was very thoroughly (if not shockingly) debunked. Nevertheless, Marder helps himself to some suspiciously similar ideas towards the end of arguing against a clear moral distinction between eating plants and eating animals (2). The impetus for his argument is a recent finding (by Falik et al.) indicating that pea plants share stress-induced chemical signals through their root systems, thus triggering defensive responses in unstressed plants. Also, didn’t you see that adorable little peas-in-a-pod doll in Toy Story 3? Put down that can of pea soup, you monster.

I will admit that last part was a rhetorical flourish (Marder’s essay never mentions Toy Story 3, the latter of which has a more plausible narrative). Rhetoric is a dangerous tool when used towards ill effect, either intentionally or otherwise. It’s only fair, then, that we should look at some of the rhetoric at work in this latest round of pea-hugging.

Summarizing the original research, Marder describes plants as capable of “processing, remembering, and sharing information,” able to “draw on their ‘memories’” and engage in “basic learning.” Going back to the journal article to which he refers, we find that peas “eavesdrop” on their neighbors “in ways that have traditionally been attributed to higher organisms” (3). Can anyone be blamed for concluding, as Marder does, that “plants are more complex organisms than previously thought” in ways reminiscent of Backster’s “primary perception” research?

Honestly: no. That plants employ complex signaling systems and information storage mechanisms goes against many of our intuitions regarding the distinction between kingdoms Plantae and Animalia, from which derives Aristotle’s claim that animal telos includes sense perception where plant telos does not. This research is surprising in that respect, so it stands to reason that our intuitions should be adjusted in light of this surprising data.