You read this right. This is a philosophical exposition of the not-particularly-philosophical question of animal rights – more precisely, why do animals have rights. If you're a fan of formal philosophy, congratulations, you're in for a treat! If you're not a fan of formal philosophy, that's entirely fine, too. You may find yourself pleasantly surprised.
Let's start with a basic observation concerning rights. What are rights? Some suggest that rights are a kind of interest – so, for instance, if I have an interest in consuming food at regular intervals, I may posit that I have a right to food at regular intervals; alternatively, if I have a burning desire to travel to space and land on Mars, one could attribute to me a right to travel to Mars… Whilst the former example seems intuitive enough, the latter seems a tad implausible – surely, we have the right to live, to food and shelter, but we do not have a right to travel to and land on Mars?
Hence a potential modification may be introduced – a right refers to a core or integral interest, an interest to which the individual agent assigns substantial importance, or that poses significant value to the agent in question in accordance with some external, objective standard of value. All in all, rights are substantial interests that matter – their reneging and non-fulfillment are problematic, and to be avoided where possible. Agents have rights if they possess core interests that are integral to their wellbeing (to what extent can wellbeing be articulated in terms that do not invoke the agent's rights? That remains to be seen).
So far, so good. And here's where the argument involving animals come in – I'd posit that animals have a limited yet significant range of interests. Animals bear interests to not be starved, to not be killed, to not endure pain, to… [insert long list of attributes that we can infer from observing animals' behaviours]. Cows do not wish to be maimed by predators – that's why they run away from threats; dogs do not seek to be eaten – indeed, their very ability to procreate and survival is contingent upon their not being eaten by whomsoever preys on them; turtles have an interest in not being tortured; hamsters in not being killed… so on and so forth.
Such interests translate to rights – or, to be more precise, through observing incidental behaviours and traits exhibited by such agents, we can come to derive rough approximation of the contents of the rights borne by animals. Here a rejoinder may be proffered – surely, animals are not agents? To attribute to them agency, or moral personhood, seems to be an excessive and unfounded leap of faith that is decoupled from empirical reality.
To which I have two responses: the first is that one does not need to possess moral agency (e.g. ability to devise and follow through on complex wills and autonomous volitions) in order to possess interests – consider someone in a perennial vegetative state, and that will not regain consciousness in the future; they may not possess the ability to exercise agency, or, indeed, to develop and hold the very thoughts that resemble the underpinning elements of moral agency. This does not preclude them from holding a right to life, purely on the grounds that life is objectively (and intrinsically) important for them (and for us, too). The second, is that certain animals do indeed, arguably, satisfy the prerequisites for moral agency. Dolphins, apes, and parrots are highly intelligent creatures – whilst their intelligence most certainly pales in comparison to ours (or at least, that's what we'd like to think is the case – sadly empirical facts suggest otherwise), they remain moral persons given their capacity to understand and formulate prerogatives in relation to themselves. It is the cognizance of selfhood that gives rise to the case for assignment of moral agency.
So what gives? The upshot is simple – animals have a right to life, given that a) they would prefer to be alive as opposed to killed, b) there exists an objectively valuable claim to life that we would respect amongst all living, breathing creatures at large, and c) the benefit of doubt and moral risk calculus suggest that we should presume that they have, indeed, the right to life (even if the probability of their possessing a right to life is miniscule, the infinitesbad of violating an agent's right to life renders the act of killing inappropriate from the perspective of moral risk-minimisation). What this entails, however, is another matter.
We have good grounds to think that the right to life is important, but not overriding. For instance, a case could be made that our right to enjoy the exquisite, delicate taste of A4 steak renders killing cows morally permissible – you may laugh at this, but this is perfectly intuitively self-explanatory and justified. Alternatively, as some other experts would suggest, it is not inherently erroneous to posit that the life of a hamster could be expended in exchange for improvement to public health outcomes (the operative question being, how much improvement is there… how significant is the positive delta?). That animals have rights, does not render their rights "trumping rights". Carnivores could rejoice… for now.