Bentham’s view was that the ability to suffer means that we ought to give at least some moral weight to a being (their capacity to suffer determining how much weight they are given). Singer’s view, when he was a preference utilitarian, was that we should equally consider the comparable interests of all sentient beings. Every classical utilitarian will give equal weight to one unit of pleasure or one unit of suffering (taken on their own), regardless of the species, gender or race of the being experiencing the pleasure or suffering. This is a pretty mainstream view within EA. If it means (as MacAskill suggests it might, in his latest book) that the total well-being of fish outweighs the total well-being of humanity, then this is not an objectionable conclusion (and to think otherwise would be speciesist, on this view).
Bentham’s view was that the ability to suffer means that we ought to give at least some moral weight to a being (their capacity to suffer determining how much weight they are given). Singer’s view, when he was a preference utilitarian, was that we should equally consider the comparable interests of all sentient beings. Every classical utilitarian will give equal weight to one unit of pleasure or one unit of suffering (taken on their own), regardless of the species, gender or race of the being experiencing the pleasure or suffering. This is a pretty mainstream view within EA. If it means (as MacAskill suggests it might, in his latest book) that the total well-being of fish outweighs the total well-being of humanity, then this is not an objectionable conclusion (and to think otherwise would be speciesist, on this view).