Why is sentience a "go to" argument for animal advocates and vegans?
Animal advocates and vegans advance the argument that animals are sentient and this means that they should be afforded a particular kind of regard. Often this means some kind of interest-based rights, but I get the feeling that for most, sentience just means that other animals feel stuff so we shouldn't be harming them.
The problem of harm is one of welfarism - that is, if we can use other animals without harming them (except for the killing part that is) there seems no real reason not to do so if there is a benefit to us from this. In the end I think the argument against this kind of animal use is from a personal sensitivity point of view - someone feels uncomfortable or sad that another animal is killed for food for example. For most people it probably is the case that as long as there is some level of good welfare, the use of animals in this way is fine.
The rights question seems to me to be a bit harder to work out. Why does "sentience" mean we should afford other animals rights? Do activists seriously believe that mice should have rights? Or, at least, the same rights as a cow? When is sentience sufficient to require rights?
This seems a rubbery question and I am not sure it reduces to any solid argument. No-one can really know what cows or mice think and how they feel about the world, so doesn't the case from sentience really just reduce to welfarism again? Why does it have to be more? Yes, I've read a few books about this but mostly it just comes down to someone's feeling that sentience demands a rights based recognition. Is there any empirical basis to this claim that doesn't simply reduce to welfarism?
If a being is not capable of suffering, there is no suffering to consider when deciding how to treat them. If a being is not capable of feeling, there is no feeling to consider when deciding how to treat them. If a being cannot experience life or enjoy life, or be miserable, what is there to take from them if they would be killed? If a being knows nothing, feels nothing and does not suffer or have any interest in not suffering, there is nothing for them to lose if they are, for example, hit or cut and killed. Destroying a non-sentient “being” that has never suffered or been sentient and will never suffer or be sentient is akin to just destroying or damaging an inanimate object; they have no experiences, no capacity for suffering or for happiness, no capacity to feel, no capacity to think or be aware of anything.
Sentience is a better factor for determining moral value than intelligence in other beings besides nonhuman animals. A person with severe mental disabilities would likely be less intelligent than your average human being, but they still feel and, therefore, certainly have moral value and should not be treated with cruelty any more than anyone else should, and they should instead be treated with compassion and given necessary support and care. I know they would still be human, but it’s similar with animals. If intelligence were to define the moral value of a being in your view, you would treat the person with severe learning disabilities as less equal than someone without learning disabilities. If intelligence were to purely define how much moral value you afford to someone, you might treat a baby as less important than your average adult human.
Also, sapience is not a good enough determiner for how to treat a being. If there was another species that were just as intelligent, caring, emotional and sentient as we are, but they were just not human beings (not sapient), it would not really be moral to treat them with any less compassion or moral value. A dog is not sapient, but they are sentient. They are capable of feeling and thinking. They are capable of suffering. Similarly, a pig, a cow, a chicken, a duck, a goat, a sheep, a turkey, a goose, a rabbit, a wolf or any of most other species of animal are not sapient, but they are still sentient. They are all capable of feeling love, pain, fear and distress. They are all capable of suffering. They are all aware, at least, to some extent. Therefore, all of those species (and all other sentient species) deserve to be loved (or at least respected and treated with kindness and compassion), and to not be treated in any way that unjustly causes them distress, fear, pain or suffering.