An argument is examined and defended for extending basic moral rights to animals which assumes that humans, including infants and the severely mentally enfeebled, have such rights. It is claimed that this argument proceeds on two fronts, one critical, where proposed criteria of right-possession are rejected, the other constructive, where proposed criteria are examined with a view to determining the most reasonable one. This form of argument is defended against the charge that it is self-defeating, various candidates for the title, (...) 'most reasonable criterion of right-possession', are critically examined, and it is argued that this criterion is to be found in the notion of inherent value: What underlies the ascription of rights to any given x is that x has value logically independently of anyone's valuing x; thus, to treat x as if x had value only if or as it served one's interests, etc., is to violate x 's rights. It is argued that many animals, owing to their being subjects of a life that is more or less valuable for them logically independently of the interests of others, can satisfy this criterion and therefore have certain basic moral rights, if humans, including the severely mentally enfeebled, do. Finally, the question, What basic moral rights do animals have? is explored. (shrink)