"When it comes to respecting someone, it is completely irrelevant whether that being can speak, whether she can think in the same way we do, or whether we have some kind of special relation with her. Because that isn't what determines whether she can be harmed or benefited by our actions. The relevant point is whether she can feel suffering or/and joy. Furthermore, if that was the case, many humans should be discriminated against too. Because there are many humans who can't talk or can't think as other humans do, and many have no one who cares for them. So if the arguments that are used to discriminate against animals were accepted, we should also discriminate against humans. These are some general arguments that are seldom used. I don't understand why not. Because debating these points, debating these issues is what will eventually lead society to a change. Of course there are other arguments involved and there are many other ways to question speciesism. My main point is we should be focused on challenging it."

“Then, I claim that if we abandon a speciesist viewpoint we should change completely the way in which we should intervene in nature. Rather than intervening for environmental or anthropocentric reasons, we should do it in order to reduce the harms that nonhuman animals suffer. This conflicts significantly with some fundamental environmental ideals whose defence is not compatible with the consideration of the interests of nonhuman animals.”

“Oscar Horta at Google Scholar”

“What happens to all the other animals that come into existence? They die, often shortly after they start to be sentient. They starve, are killed by other animals or in other painful ways, and, because they die so soon, they do not have the chance to have many other experiences apart from the suffering of their death. This means that they may never have any positive experiences at all, or just have very few ones. Other animals may be able to survive a bit longer and have some more positive experiences, yet not enough to outweigh the suffering they endure because of the hardships of their existence which eventually lead them to their death. These animals experience more suffering than well-being in their lives.”

“Part of society still confuses two movements that differ markedly: environmentalism and anti-speciesism. These facts highlight the clear differences between these two different movements. The ecologist defends the maintenance of natural spaces and species and consider animals as part of the environment that surrounds us humans. Antispeciesism, however, does not see animals as simply a part of our environment. On the contrary, it sees them as part of our own group: that of individuals, beings that can suffer and enjoy and therefore, defend the animals as such. Environmentalism defends killing animals when it benefits the conservation of an ecosystem or a species, a position that does not hold in the case of human beings. Why? Because it does not consider that animals of species other than ours have interests that we have to respect. Antispeciesism considers that such a position is a discrimination, a discrimination of those who do not belong to our species. Therefore, it advocates to respect non-human animals, as we advocate respect for human beings.”

“This means that the number of animals that come into existence only to die shortly after is extremely high. On average, if we consider a context in which populations remain stable at least in the mid term, for each animal that reproduces, only one of her or his offspring survives . This means that all the rest of the animals die. Many of them die shortly after coming into existence. These animals starve to death, are eaten by other animals, or die for other reasons that usually entail a great deal of suffering. This means that an enormous number of animals come into existence only to suffer. Their lives contain virtually no enjoyment, since they die shortly after they start to exist. However, their lives do contain significant suffering, because of the painful ways in which they die. They thus live lives in which disvalue outweighs value. Living their lives causes them more harm than good. In fact, in many cases it causes them great harm and no good at all.”

“Similarly, some people have argued that the harms suffered by animals in the wild should not concern us because they are natural. This sounds like a speciesist claim, given that such a view is rarely held when humans suffer those harms. Also, it seems that if the animals themselves could have a say on this, they would clearly prefer to be spared those harms, as we would in their situation.”