A curious thought hit me today: What could it mean for something, say pollution, to be bad for the earth? We have, I think, a fairly good idea of what it is for something to be good or bad for a human, a dog, a wasp, a tree and maybe even a bacterium. But for a planet? For humans, dogs, etc., there are roughly three accounts of well-being: (a) the hedonist account that well-being is pleasure and absence of pain, (b) the desire account that well-being is (roughly) fulfillment of desires and lack of frustration of desires, and (c) the flourishing account. Now, (a) requires consciousness and (b) requires mind, so neither is applicable to a tree, a bacterium or the earth.
That leaves the flourishing account. But while I have some idea about canine and waspish flourishing, I have very little idea about planetary flourishing. For instance, does hosting life make a planet flourish, or to the contrary, do planets flourish more when they are devoid of life? After all, if the average member of a natural kind is likely to have a normal degree of flourishing, it appears that lifeless planets have a normal degree of flourishing. So as long as we don't literally blow the earth into pieces, it seems that whatever pollution we inflict on it, we won't push it below the normal level of well-being.
But perhaps we need to distinguish different kinds of planets, and different kinds of planets have different kinds of flourishing. Thus, maybe, a planet in a "habitable zone" in a stellar system has the support of organic life as part of its flourishing. But what kind of organic life is needed for flourishing? Is the planet better off for hosting more complex life-forms? (Is a house better off for having people rather than geckos in it?) Or for a greater diversity of life-forms? (Is a house better off for having people and cockroaches rather than just people?) It seems plausible that unless we have a metaphysical teleology, either of the Aristotelian or the theistic sort, for planets in the habitable zone, these questions have no answer. And even if we have such a teleology, the epistemology of that teleology will be difficult, because the earth is the only habitable planet we know of, and typically we learn about the teleological properties of a natural kind by observing multiple instances.
But perhaps it is a mistake to think of the earth as rocks, water and atmosphere. Rather, the suggestion goes, the ecosystem is not just hosted by the earth, but is a part of the earth. I am not sure we should buy that. While parthood might not in general be transitive, it seems plausible that since we are parts of the ecosystem, then if the ecosystem were a part of the earth, we would be parts of the earth. But surely we are not parts of the earth. We live on earth, but we are not parts of it any more than we are parts of the galaxy (though the earth is a part of the galaxy).
But let us grant that the ecosystem is a part of the earth—or maybe that "the earth" is sometimes a metonymy for the ecosystem. In that case, pollution that causes destruction of a part of the ecosystem without a compensating growth elsewhere does seem to be contrary to the flourishing of the earth. But more detailed study of flourishing still seems mired in epistemic problems. It is very hard to figure out the teleology of the ecosystem as a whole, unless we accept revelation and say that the teleology is the support of humanity.