There is no logically compelling reason for assuming that a factual difference in ability between two people justifies any difference in the amount of consideration we give to their needs and interests. The principle of the equality of human beings is not a description of an alleged actual equality among humans: it is a prescription of how we should treat human beings.
Sometime I shy away from comparing massive animal abuse to the Holocaust or slavery. I'm afraid that people will say What? You think Jews are like animals? You think black people are animals?
Well, you know what? They ARE animals. We are ALL animals. We're more genetically similar to chimpanzees than chimpanzees are to gorillas. Yet, we separate ourselves from the other animals.
Many people argue against slavery and other forms of discrimination by declaring that all people are created equal. I think most educated people in this century can agree on that point. There's no group of people that's superior to another group of people. What Singer argues though is that equality in intelligence is NOT a good reason for avoiding slavery and abuse. Why? Because WITHIN each of these groups, we have various levels of intelligence and abilities.
The existence of individual variations that cut across the lines of race or sex, however provide us no defense at all against a more sophisticate opponent of equality, one who proposes that say the interests of all those with IQ scores below 100 be given less consideration than the interests of those with ratings over 100. Perhaps those scoring below the mark, in this society, would be made the slaves of those scoring higher. Would a hierarchical society of this sort really be so much better than one based on race?
Some animal rights activists try to push us into Vegetarianism by showing us how intelligent animals are. I do applaud their efforts because I think animal intelligence is fascinating. Animals have memory. They use tools. They make tools. They lie. They are so much more than many people dare to imagine.
Yet, does this matter? Does something need a certain level of intelligence for us avoid abusing it?
Peter Singer tells a story about a baby born in Italy without a brain stem. There was no hope for the baby, so it's generous parents wanted to donate it's organs so other babies could live. Their request was denied. It is NOT okay to end a human life--not even a life that is completely mentally and emotionally empty, and will be a financial drain on society. Yet, a few months later a completely healthy baboon with much more intelligence than the baby-without-a-brain stem was killed so it's organs could be given to a human.
The belief system that supports the decisions above is called speciesism. It's the belief that one type of animal is superior to another animal--not on a basis of intelligence. But simply for what it is or what it is not.
I think we can compare all this to Harry Potter. Wizards have more abilities than Muggles. In JK Rowlings world, the Wizards are more interesting, and they have powers. The Muggles are a bit oblivious. They have less powers. In terms of abilities, they are inferior to the Wizards.
But what does that mean for the Wizards? How should they treat the Muggles? Should they kill them in painful ways and then turn them into delicious treats? Should they use them for experiments in magic? Or do they need to go in the opposite extreme-- include Muggles in everything? Give them the exact same rights and opportunities as the wizards?
The latter idea would make about as much sense as treating your dog the exact same way you treat your child. Give him his own bedroom. Let him eat at the table with you. Give him a birthday party. I don't think any of that's really necessary.
The Wizards didn't treat the Muggles like Wizards. But for the most part, they did treat them well. Not only did the Wizards avoid harming the Muggles. In some instances, they actively worked to protect the Muggles.
I don't feel it's our job to give animals equal rights. I think it's our job to avoid harming animals and protect them as much as possible.
I don't think other animals are equal to humans. Just like I don't think I'm equal to Albert Einstein. But I do think my right to be protected from suffering is equal to that of people as brilliant as Einstein. And I think an animal's right to be protected from suffering is equal to mine.