(Original post by TheDefiniteArticle)
Morality is a calculus which dictates behaviour based on what is best for the class of beings deemed morally important. It is silly to decide first what the content of morality is, and then the beings to which morality applies. Unless, of course, you define the class of beings as 'those capable of experiencing suffering', but that needs justifying - it's very far from being able to be taken as obvious.
But, if morality is to do with anything, it's surely to do with the quality of experience of conscious creatures, and how actions affect it. For example, if the universe were filled only with rocks, there would be no reason to care how anything turned out, because there are no conscious perspectives to whom it could matter in any way. It's only because creatures exist (e.g. us), and we can experience good and bad states of conscious experience, that things do, in that sense, matter. Morality must therefore be concerned with those conscious perspectives and their vulnerability to positive and negative states of experience, i.e., suffering, satisfaction, and so on. Any other conception of morality I think fails to account for why it matters or is relevant to anyone or anything, since it detaches itself from the only things that it can matter or be relevant to - conscious creatures and their nature of experience.
There are many creatures that have a stake in their conscious experience of course, not just humans. Vertebrates, and possibly invertebrates and other animals are also vulnerable to different states of conscious experience (positive and negative) in the same way - although likely not to the same degree - as we are. Therefore, any moral behaviour should also, it seems to me, take their perspectives into account.