The admissions that pleasures differ in kind, and that actions are already
classified; the acknowledgment that happiness includes the happiness of
others, as well as of ourselves; the confusion (not made by Aristotle)
between conscious and unconscious happiness, or between happiness the
energy and happiness the result of the energy, introduce uncertainty and
inconsistency into the whole enquiry. We reason readily and cheerfully
from a greatest happiness principle. But we find that utilitarians do not
agree among themselves about the meaning of the word. Still less can they
impart to others a common conception or conviction of the nature of
happiness. The meaning of the word is always insensibly slipping away from
us, into pleasure, out of pleasure, now appearing as the motive, now as the
test of actions, and sometimes varying in successive sentences. And as in
a mathematical demonstration an error in the original number disturbs the
whole calculation which follows, this fundamental uncertainty about the
word vitiates all the applications of it. Must we not admit that a notion
so uncertain in meaning, so void of content, so at variance with common
language and opinion, does not comply adequately with either of our two
requirements? It can neither strike the imaginative faculty, nor give an
explanation of phenomena which is in accordance with our individual
experience. It is indefinite; it supplies only a partial account of human
actions: it is one among many theories of philosophers. It may be
compared with other notions, such as the chief good of Plato, which may be
best expressed to us under the form of a harmony, or with Kant's obedience
to law, which may be summed up under the word 'duty,' or with the Stoical
'Follow nature,' and seems to have no advantage over them. All of these
present a certain aspect of moral truth. None of them are, or indeed
profess to be, the only principle of morals.

And this brings us to speak of the most serious objection to the