Those who accept speciesism often do so because they believe humans “superior” on the basis of rationality and empathy, but in a terrible twist of irony, reject all rationality and empathy in refusing to acknowledge sentience as the morally relevant characteristic on which to base inclusion in the moral community. In refusing to apply such rationality and empathy, they behave far worse than the nonhuman animals toward whom they feel so superior: They are like an odd bird who has functioning wings, but refuses to fly when it is appropriate to do so.
Those who reject speciesism apply that rationality and empathy – ever so exalted but forgotten in speciesism – in acknowledging sentience as the morally relevant characteristic on which to base inclusion in the moral community. Lifelong veganism is the natural outcome of such rationality and empathy. Being a vegan is what it means to be fully human; to live up to one's potential in accordance with the rationality and empathy that are supposedly strong human traits.