, involved in the greater or less reliance which they
can place in each other's word, acts the part of one of their worst
enemies. Yet that even this rule, sacred as it is, admits of possible
exceptions, is acknowledged by all moralists; the chief of which is when
the withholding of some fact (as of information from a male-factor, or
of bad news from a person dangerously ill) would preserve some one
(especially a person other than oneself) from great and unmerited evil,
and when the withholding can only be effected by denial. But in order
that the exception may not extend itself beyond the need, and may have
the least possible effect in weakening reliance on veracity, it ought to
be recognized, and, if possible, its limits defined; and if the
principle of utility is good for anything, it must be good for weighing
these conflicting utilities against one another, and marking out the
region within which one or the other preponderates.

Again, defenders of utility often find themselves called upon to reply
to such objections as this--that there is not time, previous to action,
for calculating and weighing the effects of any line of conduct on the
general happiness. This is exactly as if any one were to say that it is
impossible to guide our conduct by Christianity, because there is not
time, on every occasion on which anything has to be done, to read
through the Old and New Testaments. The answer to the objection is, that
there has been ample time, namely, the whole past duration of the human
species. During all that time mankind have been learning by experience
the tendencies of actions; on which experience all the prudence, as well
as all the morality of life, is dependent. People talk as if the
commencement of this course of experience had hitherto been put off, and
as if, at the moment when some man feels tempted to meddle with the
property or life of another, he had to begin considering for the first
time whether murder and theft are injurious to human happiness. Even
then I do not think that he would find the question very puzzling; but,
at all events, the matter is now done to his hand. It is truly a
whimsical supposition, that if mankind were agreed in considering
utility to be the test of morality, they would remain without any
agreement as to what is useful, and would take no measures for having
their notions on the subject taught to the young, and enforced by law
and opinion. There is no difficulty in proving any