ence of an acknowledged first
principle has made ethics not so much a guide as a consecration of men's
actual sentiments, still, as men's sentiments, both of favour and of
aversion, are greatly influenced by what they suppose to be the effects
of things upon their happiness, the principle of utility, or as Bentham
latterly called it, the greatest happiness principle, has had a large
share in forming the moral doctrines even of those who most scornfully
reject its authority. Nor is there any school of thought which refuses
to admit that the influence of actions on happiness is a most material
and even predominant consideration in many of the details of morals,
however unwilling to acknowledge it as the fundamental principle of
morality, and the source of moral obligation. I might go much further,
and say that to all those _a priori_ moralists who deem it necessary to
argue at all, utilitarian arguments are indispensable. It is not my
present purpose to criticise these thinkers; but I cannot help
referring, for illustration, to a systematic treatise by one of the most
illustrious of them, the _Metaphysics of Ethics_, by Kant. This
remarkable man, whose system of thought will long remain one of the
landmarks in the history of philosophical speculation, does, in the
treatise in question, lay down an universal first principle as the
origin and ground of moral obligation; it is this:--'So act, that the
rule on which thou actest would admit of being adopted as a law by all
rational beings.' But when he begins to deduce from this precept any of
the actual duties of morality, he fails, almost grotesquely, to show
that there would be any contradiction, any logical (not to say
physical) impossibility, in the adoption by all rational beings of the
most outrageously immoral rules of conduct. All he shows is that the
_consequences_ of their universal adoption would be such as no one would
choose to incur.

On the present occasion, I shall, without further discussion of the
other theories, attempt to contribute something towards the
understanding and appreciation of the Utilitarian or Happiness theory,
and towards such proof as it is susceptible of. It is evident that this
cannot be proof in the ordinary and popular meaning of the term.
Questions of ultimate ends are not amenable to direct proof. Whatever
can be proved to be good, must be so by being shown to be a means to
something admitted to be good without proof. The medical art i