Plato’s reason for claiming that the life of the Philosopher has more pleasure than that of the Sensualist is palpably inadequate. The philosopher, h… - Henry Sidgwick

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 viewed, or less certainly knowable or attainable by him.

Is it total or average happiness that we seek to make a maximum?...we foresee as possible that an increase in [population] numbers will be accompanied by a decrease in average happiness...if we take Utilitarianism to prescribe, as the ultimate end of action, happiness on the whole...it would follow that, if the additional population enjoy on the whole positive happiness, we ought to weigh the amount of happiness gained by the extra number against the amount lost by the remainder. So that, strictly conceived, the point up to which, on Utilitarian principles, population ought to be encouraged to increase, is not that at which average happiness is the greatest possible...but that at which the product formed by multiplying the number of persons living into the amount of average happiness reaches its maximum.

Many religious persons think that the highest reason for doing anything is that it is God’s Will: while to others ‘Self-realisation’ or ‘Self-development’, and to others, again, ‘Life according to nature’ appear the really ultimate ends. And it is not hard to understand why conceptions such as these are regarded as supplying deeper and more completely satisfying answers to the fundamental question of Ethics, than those before named: since they do not merely represent I what ought to be, as such; they represent it in an apparently simple relation to what actually is. God, Nature, Self, are the fundamental facts of existence; the knowledge of what will accomplish God’s Will, what is, ‘according to Nature’, what will realise the true Self in each of us, would seem to solve the deepest problems of Metaphysics as well as of Ethics. But […] [t]he introduction of these notions into Ethics is liable to bring with it a fundamental confusion between “what is” and “what ought to be”, destructive of all clearness in ethical reasoning: and if this confusion is avoided, the strictly ethical import of such notions, when made explicit, appears always to lead us to one or other of the methods previously distinguished.