Holmes: The idea that plants “value” has always been contentious to me. Does this mean any more than simply that they have a good of their own? That things are instrumentally valuable for them? I’m thinking that part of what you have in mind is that living beings actively do things to promote their own good. Is that the sense in which “they value?” Valuing is active, I’m assuming. Ned
Plants have a good of their own, and they do things actively, proactively (though not consciously), to promote their own good. They defend their goods = They defend what they value. These behaviors have adaptive value. Such value is a standard biological term. Otherwise they would be dead and their species extinct.
So plants, over time, not only have a good of their own they have adaptive fit in their ecosystems. The result is the elaboration of biodiversity and biocomplexity, continuing over millennia, that humans, when they lately appear, do find valuable in various ways.
I realize that for a hard-nosed philosopher, that fact alone does not warrant the conclusion that they have intrinsic value. One has to run the biological facts through another philosophical filter to warrant any conclusions about real value. (O'Neill's 1992 paper, John Nolt's two papers in Env Ethics, 2006, 2009).
What is the character of this philosophical filter. I don't think anyone has given a satisfactory to this question, beyond the fact that in some humans judge that some plants with a good of their are really good, and others, such as poison oak, have a good of their own but are bad kinds. This amounts to little more than a humanistic prejudice filtering biological facts.
I do the best I can with this in my New Env Ethics, (Routledge, 2012) p.96-107, pp. 116-122. You can read that over.