Gary Francione has an article at Aeon arguing that it is immoral to own animals and morally necessary to be a vegan. It's long an assertion and short on argument, but what argument there is, has a number of problems. A few points.
Francione says:
The Western view was that we could have moral and legal obligations that concerned animals but were not owed to them. To the extent that the cruel treatment of animals was thought to present a moral problem, it was only because it made us more likely to be cruel to other humans. But any obligation to be kind to animals merely concerned animals; the obligation of kind treatment was owed only to other humans. This was the view of Immanuel Kant, Thomas Aquinas and others.
This is not really true of Kant. On Kant's view, we owe other human beings not qua individuals but qua rational; that is, our duties are duties to humanity in the sense of 'rational nature'. But for Kant this grounding of duty on humanity applies to animals as well; we owe other animals certain actions insofar as they are analogues of humanity. Kant is quite explicit that we have duties to animals; they are just more indirect than those to human beings. Something broadly similar can be said of Aquinas. What makes compassion a virtue is its relation to human beings, but animals are naturally objects of compassion because their afflictions stir up the same feelings as the afflictions of human beings, and we are obligated to be compassionate in any appropriate situation. Thus exactly the same obligation covers both man and beast, it just does so for different reasons, and, because it does so for different reasons, that obligation is not always going to be satisfied in the same way for both.
Part of Francione's mistake (which is a common one) is that he assumes there is a very sharp distinction between an obligation that are about someone and an obligation 'to' them and puts all the emphasis on the latter. But the content of our obligations comes from the former, not the latter, which really concerns the reasons for the obligation rather than the content. (Of course, in colloquial speech we often don't distinguish them at all, since in many simple cases, obligations are 'about' those 'to' whom we have them.)
Likewise, Francione says, "Animals supposedly were not rational, self-aware or able to use concepts, and this was thought to justify our treating them as having no moral value." But that animals should be treated as having no moral value has never been in any way the common Western view Francione claims; indeed, I suspect you could not find any definite statement of this at all before the last two hundred years.
While he does later on get Bentham's position roughly right, he notably doesn't look at why Bentham takes the position he does. Bentham thinks that enjoyment and suffering are the only foundations for moral concern in any case. Thus he would entirely reject the distinction Francione makes between 'persons' and 'quasi-persons'; Bentham wouldn't think the category of person has much relevance here, and he is advocating treating animals in exactly the same way as human beings. He doesn't think our interest in continuing to live is relevant, either, except insofar as it expands our enjoyment or suffering.
When Francione gets away from history and to the present, his argument doesn't much improve:
Is any of this animal use necessary? Putting aside instances where people are stranded on lifeboats or desert islands, or otherwise facing imminent starvation, it is not necessary for humans to eat animals or animal products. Indeed, for several decades, a growing number of mainstream healthcare professionals have been telling us that animal foods are not only not necessary for, but are actually detrimental to, human health.
This is a baffling argument. It is in fact necessary for humans to eat animal products. We are omnivores who have been eating animal products for our entire discernible evolutionary history, and our bodies have a dependency on them. There are things that we need that no plants make at all. In the long term, you can literally damage your brain by imposing a vegan lifestyle without proper planning. Now, it is true that we live in an age of wonders, and we can synthesize these missing elements, either chemically or indirectly by cultivating non-plant organisms (algae or various kinds of bacterial colonies) so as to produce them. This is why generally serious vegans are big on things like spirulina (although spirulina is not itself a particularly great source). Even when we can get the nutrient from plants, it's not necessarily easy to get it in adequate quantities from those sources. And it would be entirely false to claim that we are currently in a position to make up synthetically all the inadequacies of an all-plant diet for the entire population of the earth.
Strict veganism, as opposed to alternatives like vegetarianism, pescetarianism, or 'loose veganism' (i.e., mostly vegan, with some limited concessions to some very occasional animal products), is a luxury lifestyle that at present can only be safely practiced by people with access to large-scale agricultural transportation and nutritional specialists. Vegetarianism, pescetarianism, and loose veganism do have problems that have to be compensated for if practiced at a large-scale, but they are much more manageable as patterns for an entire society. (India is probably the large society that actually comes closest to what Francione would consider the ideal. There's an extremely good reason why so much of Indian life has been associated with the milk cow -- a vast quantity of milk products is the only thing that makes such a society possible.)
