On this page, I would like to present some arguments. They will be concise. I will not explore the acceptability of each premise in great detail. I will leave that for other articles and other advocates. There is value in being able to see some of the arguments boiled down to their bare necessities. I do not claim that these are necessarily the best arguments to be made or that they are formulated perfectly, but they are my current approximations. These are works in progress only.
Onus of proof
First, one might argue that the onus of justifying the causing of suffering and death to nonhuman animals is on those who would propose to do so. On the one hand, it is culturally common and accepted to cause said suffering and death but on the other hand, these practices result in extensive harm whereas a vegan approach does not and in that regard, the practices leading to suffering and death must be justified if it is to be accepted, regardless of how common and accepted it is. In discussions on the justification for these practices and attitudes, I try not to forget that a true starting point ought to be the holder of these harmful practices providing a justification and only if it is on the face of it reasonable, then a prima face case is made and only then is a counterargument called for. In that regard, it is usually appropriate or necessary to provide counterarguments for commonly proposed justifications.
A justice and rights argument
A basic right is a mechanism by which we protect interests in not being treated as the property of others. No rights is justified if it involves breaching the basic rights of others.
Just (non-arbitrary) application of basic rights is a fundamental necessity of a coherent and useful ethical system.
Justice involves treating similar cases similarly and treating cases dissimilarly only where they are relevantly and sufficiently dissimilar.
The only relevant feature regarding the just application of basic rights is whether the being to have rights has interests to be protected.
The only relevant distinction between just application of rights and no rights is whether the 'thing' in question has interests to be protected. Things without interests cannot have rights and things with interests ought to have rights.
Sentient beings have interests (in experiencing pleasure and not pain) and many nonhuman animals are sentient beings.
Mere species membership, as well as whether the being is capable of producing language or can generate similar I.Q. scores are all irrelevant in the context of the just application of rights.
Therefore, rights ought to justly apply to all sentient beings regardless of their species membership.
Some nonhuman animals are sentient
Humans and other animals share an evolutionary history including the adaptive function for pain, to escape stimulation detrimental to survival and reproduction.
Humans and other sentient beings share a similar anatomy and physiology, in particular as it relates to pain and pleasure responses.
Nonhuman sentient beings react similarly to humans when experiencing what we know to generate painful experience.
There is no reason to assume many nonhumans lack the ability to experience pain and pleasure.
If an animal experiences pain then there must be an awareness that the experience is occurring to them.
Many humans and many nonhumans are sentient, that is, they can experience pain and experience that it is them experiencing the pain.
Rights rather than welfare
As long as nonhuman animals are considered property, no welfare actions will promote beneficial changes beyond that which is financially beneficial for animal use industries.
Furthermore, there is no empirical evidence to suggest that welfare actions do result is less suffering.
As long as nonhuman animals are deemed property, no balance between the interests of animal's interests and their owner's interests can be achieved because the owner's interests will always trump the interests of their property.
Welfare and regulation approaches pacify people from recognizing the wrongness of animal use; it makes them feel as though the problem is solved.
Therefore, welfare actions do not bring about less suffering.
Rights, by their nature, protect the interests of the rights holder.
Therefore, the rights approach result in less suffering and death and welfare approach does not.
Consuming animal use products causes suffering
Causing suffering in nonhuman animals is morally wrong.
Being a consumer of products that necessitate the causing of suffering to nonhuman animals causes a demand for such products.
Therefore, Being a consumer of products that necessitate the causing of suffering to nonhuman animals is morally wrong.
Speciesism
Unjust discrimination is morally unacceptable.
Sexism, racism, heterosexism are examples of unjust discrimination.
Speciesism is also an instance of unjust discrimination.
If sexism, racism or heterosexism are morally unacceptable, then so too must be speciesism.
Rights rather than regulation
We deem rape to be morally unacceptable (because it violates basic rights).
We abolish rape in the form of laws rather than regulating its performance and thereby encouraging humane rape.
We do this because if it is unacceptable, then no performance of it is acceptable and we ought not condone any part of it.
Just as there can be no coherence to the notion of regulating humane rape because we soundly reject its acceptability, there can be no coherence to the notion of humane animal use.
Just as we abolish rape completely, we ought abolish exploitation of animals rather than regulate the exploitation of animals.