Ethical Extensionism under Uncertainty of Sentience: Duties to Non-Human Organisms without Drawing a Line

Ethical extensionism generally involves drawing one or more lines of moral standing. I argue (i) for all living organisms, there is a non-zero probability of sentience and consciousness, and (ii) we cannot justify excluding beings from consideration on the basis of uncertainty of their sentience, etc., and rather we should incorporate this uncertainty into the strength of our moral responsibilities. This use of probabilities differs critically from multi-criteria theories of moral standing and those that assign benefit of the doubt, which involve unjustified exclusions and dilutions of duties. From uncertainty rises certainty: we have duties to non-human organisms, although they may often be minor. This modi-fication of extensionist ethics provides foundation for an environmental ethic that parallels interpersonal and animal welfare ethics, and it suggests that we owe much greater concern to ‘lower’ organisms than they are typically given.