Once we separate the objective value concept of a being's good from subjective value concepts, there is no problem about understanding what it means to benefit or harm a plant, to be concerned about its good, and to act benevolently toward it. We can intentionally act with the aim of helping a plant to grow and thrive, and we can do this because we have genuine concern for its well-being. As moral agents we might think of ourselves as under an obligation not to destroy or injure a plant. We can also take the standpoint of a plant and judge what happens to it as being good or bad from its standpoint. To do this would involve our using as the standard of evaluation the preservation or promotion of the plant's own good. Anyone who has ever taken care of flowers, shrubs, or trees will know what these things mean. (Paul W. Taylor, Respect for Nature: A Theory of Environmental Ethics [Princeton: Princeton University Press, 1986], 67-8)I'm reminded of Merlin in That Hideous Strength by C. S. Lewis whose order did not permit him to use an edged tool on anything living. Come to think of it, the same reasoning that can produce vegetable rights can also produce bacterial rights. To quote from the first “Interphase” of Blood Music by Greg Bear:
But wait, there's more. There's a theory that life started as a type of clay (see Genetic Takeover by A. G. Cairns-Smith). We can expect dirt-rights activists someday. Of course, that will include the right to not be humiliated, so the phrase “dumb as dirt” will have to go…
Each hour, a myriad of trillions of little live things—microbes, bacteria, the peasants of nature—not counting for much except in the bulk of their numbers and the accumulation of their tiny lives. They do not perceive deeply, nor do they suffer. A hundred trillion, dying, would not begin to have the same importance as a single human death.
Within the ranks of all creatures, small as microbes or great as humans, there is an equality of “elan,” just as the branches of a tall tree, gathered together, equal the bulk of the limbs below, and all the limbs equal the bulk of the trunk.
We believe in this as firmly as the kings of France believed in their hierarchy. Which of our generations will come to disagree?