Philosophical justifications for the extirpation of non-indigenous species: the case of the grasshopper Schistocerca nitens (Orthoptera) on the Island of Nihoa, Hawaii

Abstract

The case of Schistocerca nitens’ establishment on the island of Nihoa presents a challenging case for conservation biologists with respect to the justification for human efforts to extirpate the insect. In justifying our actions we seek reasons that are ecologically plausible (i.e., consistent with empirical and theoretical understandings of science), ethically compelling (i.e., based on sound reasoning from well-established moral principles), and logically consistent (i.e., avoiding fallacies and contradictions). Our analysis shows that the conventional arguments for conservation programs do not meet these criteria in the case of S. nitens. The following reasons fail on the basis of ecological, ethical, or logical standards: the protection of biodiversity, avoidance of ecological harm, biological qualities of the invasive species (herbivory, fecundity, mobility, recency, and functional integration), anthropogenic basis of arrival, harmfulness or unnaturalness of human agency, the interference with ecological processes, or disturbance of equilibria. Rather, we suggest that an aesthetic argument provides an ecologically, ethically, and logically sound basis for conservation biologists to justify taking action against the grasshopper. The aesthetic concept of a “thick sense” of beauty gives rise to a compelling moral case for extirpation based on virtue ethics in a manner similar to the argument against tolerating roadside litter.