Do humans have a greater right to live than other animals? If so, would beings of much greater intelligence and perception hold that same right over humans?

Good questions! I've been a vegetarian for 38 years and believe that humans should not kill animals for food, clothing or sport. One way to think about this is to ask what it is that makes life valuable. Some think that life itself is valuable, but that isn't plausible given that plants are alive and it doesn't seem to be morally wrong to weed your garden.

Another possibility is that what makes life valuable is sentience. If that's true, then sentient animals (and not plants) would have a moral claim on us, insofar as we have a duty to protect what is valuable. (Though one needs to ask here: what is our duty to protect what is valuable? How far does that duty extend? Are there different sorts of value, some of which have a greater claim on us than others?)

Even if sentience is valuable, however, some argue that humans have capacities that are more valuable still, such as the ability to reason, to value things, to create systems of norms, even morality itself. A challenge arises here, however, since most people would argue that human beings have equal moral standing, but of course they aren't equal in their abilities to reason, or as you mention, in their intelligence. So what gives humans their special value must be something that humans, qua humans, have, such as being of a kind that has a potential to reason, value, and such. Otherwise, we would have a lesser duty to protect infants, the developmentally disabled, the brain injured, etc. The idea is that this potential doesn't come in degrees, but comes with being a member of a certain kind, the human kind, and possibly kinds of more advanced rational, valuing beings we haven't met yet. If what makes life (most) valuable is this capacity, however, then more advanced beings wouldn't have a greater right to live because they would share this valuable capacity with us.

Even if we allow that humans are more valuable than animals, however, it doesn't follow that humans have a right to kill animals to eat them or wear their skin, or torture them in order to pursue knowledge for its own sake. As long as we grant that sentience is valuable, we may have a duty to protect animals from unnecessary pain and suffering. To the extent that we can argue that animals have interests (e.g., not to be killed, to live a life appropriate to their species), it is plausible that they have a moral claim on us to respect those interests. These are just the first moves in the discussion, however, since many are keen to defend human killing of animals as morally permissible. Michael Pollan has an essay, "An Animal's Place" in the New York Times, Nov. 10, 2002 that is worth reading as a next step.

I am not a vegetarian but I think I should be. I would not couch the issue in rights language but putting animals through suffering just so I can have my New York Strip Steak just seems wrong to me. Given human history, I cannot imagine what kind of arguments we humans could muster if aliens came down and proposed to us as a food source.

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