Veganism is a moral obligation

I hope we have a fruitful conversation. The ArgumentPremise 1: It is wrong to unnecessarily kill humans to eat their flesh. Premise 2: One must be able to identify a difference between humans and animals that if present in both, would justify unnecessarily killing both for their flesh. Conclusion: In the absence of naming such a difference, unnecessarily killing animals for their flesh is wrong. Now, this argument is often misunderstood so I will do my best to explain the nuances of it in hopes that my opponent will not attempt to knock down a mere straw man. The first thing to notice about this argument is that there really are only two assumptions being made here. Assumption 1: Humans are of moral value, and therefore it is wrong to kill humans for their flesh especially for unnecessary reasons. To be clear, it is often debated upon what it means for something to be necessary or unnecessary. Although I think defining what is absolutely necessary can be difficult, it can be agreed upon that anything to do with pleasure, convenience, or habit is indeed unnecessary. So anytime I use the term "unnecessary", this is what I'm referring to, and I think we can both agree on that. Assemption 2: Logical consistency is important. This I think, is an assumption that needs no justification, for if you deny this, we have nothing to argue about. Now, onto the actual argument. P1. It is wrong to unnecessarily kill humans to eat their flesh. One of the strong points about this argument is that it is not dependent on a subjective or objective view or morality. One can think morality is either and still accept this argument. As I stated in Assumption 1, all one has to do is accept that humans are valuable at all, subjectively or objectively, and as long as they also value logical consistency, the argument still works. I am going to assume that my opponent will accept this premise, and therefore no further justification needs to be made. If humans are valuable at all, killing them for unnecessary reasons is wrong. If it is unnecessary to eat their flesh, then killing them for that reason is therefore wrong and we are morally obligated not to do it. P2. One must be able to identify a difference between humans and animals that if present in both, would justify unnecessarily killing both for their flesh. This premise really is the crux of the argument, and generally the part that most people misunderstand. I am not trying to say here that there is no difference between non-human animals (ie. pigs, cows, chickens, etc - for now I will just use the term "animals") and humans. Rather, what I am saying is that if one is going to treat animals differently than humans, we must justify that difference in treatment. So what I am doing here is asking my opponent to identify a difference between humans and animals, that if present in both, would justify treating both in the same way. If we treat animals differently merely on the basis that they are different, and no actual "justifying" difference is given, then we are being inconsistent, and therefore hypocritical. So, I challenge my opponent to name the trait or difference that is either present or lacking in animals that justifies unecessarily killing animals for food, but not humans. If my opponent believes he/she has found such a difference, the litmus test is to apply the difference to humans. When applied to humans, if the trait justifies killing humans uncessarily for food as well, then indeed my opponent will have succeeded. If, however, the trait does not work in the human context, then it is hypocritical to say it works in the animal's context - otherwise you are just appealing to mere difference without an actual justification. I will provide a few possible examples for my opponent, in hopes to shoot down any possible justifications he/she will try to deploy. Difference 1. Animals are not as intelligent as us. Lets apply this difference to the human context and ask "if a human is not as intelligent, does that make it morally permissible to unnecessarily kill that human for their flesh? " We do, in fact, have many humans who are mentally disabled and have the cognitive capacities of sometimes less than a pig for example. Does this make it okay to kill those mentally disabled humans? The answer clearly is no, and therefore if it doesn't work in the human context, it clearly isn't a difference that justifies treating animals that way either. If we use this as a justification, we are being hypocritical and it would be a double standard. Difference 2. Animals do not have the ability to understand social/moral contracts. Some will say that because animals cannot reciprocate social contracts (ie. I won't kill or harm you, and so you don't kill or harm me) then that makes it okay to unnecessarily kill animals for their flesh. However, if we apply this difference to the human context, it doesn't work. We have many examples of indigenous and uncontacted tribes in the amazon or other places around the world. They do not understand the social contracts of the modern world, and anytime we try to approach them, they throw spears and shoot arrows. They are, for all intents and purposes, unable to engage in a social/moral contract with us. Does this make it okay to unnecessarily kill them? The answer clearly is no, and therefore it doesn't work in the animal context. Difference 3. Animals don't understand morality/abstract concepts. If a human couldn't understand abstract concepts (and therefore morals), would that make it okay to kill them unnecessarily. The answer again, is no. We have many examples of this again with mentally disabled humans or infants/toddlers who cannot understand these concepts. If it is not okay to kill the disabled human or infant for lacking these traits, but it does work in the animal context, then we are holding a double standard and being inconsistent. Although I won't go through them all, there are many other differences that one can name that don't work - morphology, concept formation (ie. self, past/future, desire to live), soul, etc). The main point is that if you can't justify killing a human for having the same difference that you use to justify killing the animal unecessarily, then you are holding a double standard and being hypocritical. If we value logical consistency, we must apply this rule. This premise really can be summarized by the following:"The catch is that any such characteristic that is possessed by all human beings will not be possessed only by human beings. For example, all human beings, but not only human beings, are capable of feeling pain; and while only human beings are capable of solving complex mathematical problems, not all humans can do this. " [1]The trait or difference that may indeed work is sentience or the ability to feel pain, which I think are deeply linked together. Sentience is the trait of having a self, or having a subjective experience of the world. Obviously, pain is an experience that can only be observed if indeed sentience exists. My opponent cannot use sentience as the difference however because almost all invertebrates, and some inverterbrates, have sentience. Are there grey areas in which it is unknown whether say insects or an oyster has sentience - yes, but grey areas do not invalidate my overall argument in the cases where sentience is quite clear. Conclusion: In the absence of naming such a difference, unnecessarily killing animals for their flesh is wrong. Therefore, in the absence of such a difference, it is hypocritical to unnecessarily kill (or harm I might add) animals for their flesh. Veganism is the a way of living which seeks to minimize or exclude such killing as far as possible and therefore if this argument succeeds, it is a moral obligation to be vegan. Citations[1] Singer, Peter. Animal Liberation. New York: HarperCollins, 2002. Print.