upon the cases in which punishment is 'unprofitable';
upon such offences as drunkenness and sexual immorality, where the law
could only be enforced by a mischievous or impossible system of minute
supervision, and such offences as ingratitude or rudeness, where the
definition is so vague that the judge could not safely be entrusted with
the power to punish.'[410] He endeavours to give a rather more precise
distinction by subdividing 'ethics in general' into three classes. Duty
may be to oneself, that is 'prudence'; or to one's neighbour negatively,
that is 'probity'; or to one's neighbour positively, that is
'benevolence.'[411] Duties of the first class must be left chiefly to
the individual, because he is the best judge of his own interest. Duties
of the third class again are generally too vague to be enforced by the
legislator, though a man ought perhaps to be punished for failing to
help as well as for actually injuring. The second department of ethics,
that of 'probity,' is the main field for legislative activity.[412] As a
general principle, 'private ethics' teach a man how to pursue his own
happiness, and the art of legislation how to pursue the greatest
happiness of the community. It must be noticed, for the point is one of
importance, that Bentham's purely empirical method draws no definite
line. It implies that no definite line can be drawn. It does not suggest
that any kind of conduct whatever is outside the proper province of
legislator except in so far as the legislative machinery may happen to
be inadequate or inappropriate.

Our analysis has now been carried so far that we can proceed to consider
the principles by which we should be guided in punishing. What are the
desirable properties of a 'lot of punishment'? This occupies two
interesting chapters. Chapter xvi., 'on the proportion between
punishments and offences,' gives twelve rules. The punishment, he urges,
must outweigh the profit of the offence; it must be such as to make a
man prefer a less offence to a greater--simple theft, for example, to
violent robbery; it must be such that the punishment must be adaptable
to the varying sensibility of the offender; it must be greater in
'value' as it falls short of certainty; and, when the offence indicates
a habit, it must outweigh not only the profit of the particular offence,
but of the undetected offences. In chapter xvii. Bentham considers the
properties which fit a punishment to fulfil these conditions.