What makes a plant biologist angry? Well, probably a lot of things – from the rising rate of plant extinction to most students saying they’d prefer to learn about animals than plants. But now there’s something new ruffling feathers (or leaves?): the idea that plants have consciousness.
Research into whether plants can think has been going on for over a decade, but this month a group of plant biologists decided they’d finally had enough. They wrote in a strongly-worded open letter that: “There is no evidence that plants require, and thus have evolved, energy-expensive mental faculties, such as consciousness, feelings, and intentionality, to survive or to reproduce.”
But this isn’t a case of science vs spooky nonsense. There’s serious research into whether plants can think, and it’s turned up with some compelling results – with papers claiming that plants have memories and that they can communicate with their peers.
So why is plant consciousness such a touchy subject? Why is it making some people so angry? That’s because consciousness is such a loaded issue. The question of whether plants can think is actually about way more than that – the debate raises deep questions about our relationship with nature as a whole, and our moral duties to protect it.
Consciousness is used by different people to mean different things, from being self-aware to being sentient. But there’s one really interesting sense of ‘consciousness’ that’s key to the furore over the minds of plants. That’s when it’s used to refer to our internal, subjective experiences of the world.
In this sense, to be conscious is to have sensations – to see colours, feel hunger, hear music, smell flowers. If you’re conscious, then there’s something it’s like to be you. You’re a subject who is experiencing the world. It doesn’t matter how complex your thoughts are – if you’re capable of having sensations and experiences then you’re conscious.
As well as pleasant sensations, being conscious means we’re subject to unpleasant ones too – including the feeling of pain. And it’s this sensation of pain that makes discussions about consciousness so loaded.
Pain is bad, right? So bad that we have a moral duty not to inflict it on others, and to prevent it where we can. In fact, on many ethical theories – like utilitarianism – the duty to reduce the amount of pain is the foundation of our whole system of morality. Ultimately, our actions are good if they mean that this unpleasant experience is felt as little as possible.
Now we see why plant consciousness is such a loaded issue. If plants are conscious, then they can probably feel pain. And if they can feel pain, then we have some kind of moral duty towards them – a duty to reduce their pain as much as possible. Maybe that’d involve not cutting down trees or stripping their bark, maybe that’d involve not plucking flowers from the grass to make daisy chains.
Whatever it is, we’d have to accept there’s a whole world of living things out there that have value and moral standing, and that we need to think about their conscious experiences. That’d be huge.