Speciesism is unjustified given a preference utilitarian framework

The argument which I will be employing was originally forwarded by Peter Singer (a preeminate preference utilitarian philosopher and animal rights activist). Therefore it is not an original argument of mine and thus Mr. Singer deserves the credit for it's original formulation. My opening argument will be brief and thus this can be seen as more of an introductory argument. I will focus on the refutations which my opponent brings with my case in the further rounds.===Maximization of preference satisfaction and morality===It is a basic premise that PU holds the maximization of preference satisfaction to be the criterion of moral behavior (hereon referred to as the Principle of Preference Maxmimization or PPM). This point is in line with the definition of PU which both my opponent and I have agreed upon. It follows that the principle which our jointly assumed ethical framework is built is a good place to start. Therefore this is probably the least controversial of the premises in the argument and the most self-explanatory.===The PPM contains no prima facie differentiation between preferences vis a vis their species===The basic premise on which preference utilitarianism is based is that the maximization of preferences is an inherently basic good. From this, one may deduce that the inherent goodness of preference maximization is not necessarily correlated to whether or not the organism experiencing them has the characteristics of a person. Humans are neither the only organisms capable of holding preferences, nor is holding preferences a universal characteristic of humans[1]. Consider the case of a braindead human and a healthy dolphin. It is obvious that the dolphin will hold more preferences and thus be capable of more preference satisfaction than the braindead person. From this, we may conclude that the dolphin is therefore a more heavily weighted moral agent than the humas. Thus, we are lead to conclude that moral weight is not necessitated by species membership only, though species may be a general indicator of how weighted an organism's preferences will be (chickens will usually hold less preferences than humans though not in every case).===Animals as moral agents capable of holding preferences===All but the most ardent Cartesian's[2] admit that animals are capable of holding preferences. On PU, this makes animals moral agents and from there, means that the preferences of animals ought to be taken into account when formulating future actions or when evaluating the morality of past ones. This does not mean that all animals are automatically on par with humans vis a vis their preferences though. A full grown adult is certainly capable of much more preference loss than a chicken or a komodo dragon in most cases. All this means is that not all preferences are not necessarily equal, though this does not mean one species will always be taken into consideration more than all others.===PU and the speciesist view of preference ignorance===It has been shown that animals (not only humans) are capable of holding preferences and are thus moral agents under PU. From this it holds that the outright dismissal of all animals (or any member of a particular species in favor of another in all circumstances) as moral agents is unjustified within a PU ethical framework. ===Sources===[1] http://www.deathreference.com...[2] http://home.cogeco.ca...