The two main philosophical approaches to animal ethics are utilitarian and rights-based. The former is exemplified by Peter Singer, and the latter by Tom Regan and Gary Francione. Philosophers draw distinctions between the rightness of an act by its consequences (consequentialism/teleological ethics, or utilitarianism), and focus on the principle behind the act.
Deontologists argue that there are acts we should never perform, even if failing to do so entails a worse outcome.
There are a number of positions that can be defended from a consequentialist or deontologist perspective, including the capabilities approach, represented by Martha Nussbaum, and the egalitarian approach, which has been examined by Ingmar Persson and Peter Vallentyne.
The capabilities approach focuses on what individuals require to fulfill their capabilities: Nussbaum (2006) argues that animals need a right to life, some control over their environment, company, play, and physical health.
Stephen R. L. Clark, Mary Midgley, and Bernard Rollin also discuss animal rights in terms of animals being permitted to lead a life appropriate for their kind. Egalitarianism favors an equal distribution of happiness among all individuals, which makes the interests of the worse off more important than those of the better off. Another approach, virtue ethics, holds that in considering how to act we should consider the character of the actor, and what kind of moral agents we should be.
Rosalind Hursthouse has suggested an approach to animal rights based on virtue ethics while Mark Rowlands has proposed a contractarian approach.
