Each person is morally obliged to regard the good of anyone else as much as his own good, except when he judges it to be less, when impartially viewe… - Henry Sidgwick

Plato’s reason for claiming that the life of the Philosopher has more pleasure than that of the Sensualist is palpably inadequate. The philosopher, he argues, has tried both kinds of pleasure, sensual as well as intellectual, and prefers the delights of philosophic life; the sensualist ought therefore to trust his decision and follow his example. But who can tell that the philosopher’s constitution is not such as to render the enjoyments of the senses, in his case, comparatively feeble?

It is in their purely physical aspect, as complex processes of corporeal change, that [physical processes] are means to the maintenance of life: but so long as we confine our attention to their corporeal aspect,—regarding them merely as complex movements of certain particles of organised matter—it seems impossible to attribute to these movements, considered in themselves, either goodness or badness. I cannot conceive it to be an ultimate end of rational action to secure that these complex movements should be of one kind rather than another, or that they should be continued for a longer rather than a shorter period. In short, if a certain quality of human Life is that which is ultimately desirable, it must belong to human Life regarded on its psychical side, or, briefly, Consciousness.

We have next to consider who the “all” are, whose happiness is to be taken into account. Are we to extend our concern to all the beings capable of pleasure and pain whose feelings are affected by our conduct? or are we to confine our view to human happiness? The former view is the one adopted by Bentham and Mill, and (I believe) by the Utilitarian school generally: and is obviously most in accordance with the universality that is characteristic of their principle. It is the Good Universal, interpreted and defined as ‘happiness’ or ‘pleasure,’ at which a Utilitarian considers it his duty to aim: and it seems arbitrary and unreasonable to exclude from the end, as so conceived, any pleasure of any sentient being.