Should we care how fish feel? In his 1789 treatise An Introduction to the Principles of Morals and Legislation, English philosopher Jeremy Bentham—who developed the theory of utilitarianism (essentially, the greatest good for the greatest number of individuals)—articulated an idea that has been central to debates about animal welfare ever since. When considering our ethical obligations to other animals, Bentham wrote, the most important question is not, “Can they reason? nor, Can they talk? but, Can they suffer?
Are you aware of any philosophers who have applied this rationale to people? Many people have very poor reasoning skills, and there may also be a technological/cultural gap. For example, no one could have expected Native Americans or Australian Aborigines to understand the people who invaded their lands.
Of course, we don't expect children to have strong or mature reasoning skills.
In summary, humans are generally treated as different than other animals because we are supposedly alone in having consciousness and/or reasoning skills. Yet not all people have good reasoning skills. It's hard to put this into a question form, so let's go with this:
What are some major philosophers or philosophical doctrines that treat humans and other animals similarly? Buddhism is an obvious example, but I'm particularly interested in knowing about notable Western philosophers who have come to similar conclusions.