encourage ignorance where the law-maker has determined to make
men know and obey, and justice to the individual is rightly
outweighed by the larger interests on the other side of the
scales.

[49] If the foregoing arguments are sound, it is already manifest
that liability to punishment cannot be finally and absolutely
determined by considering the actual personal unworthiness of the
criminal alone. That consideration will govern only so far as the
public welfare permits or demands. And if we take into account
the general result which the criminal law is intended to bring
about, we shall see that the actual state of mind accompanying a
criminal act plays a different part from what is commonly
supposed.

For the most part, the purpose of the criminal law is only to
induce external conformity to rule. All law is directed to
conditions of things manifest to the senses. And whether it
brings those conditions to pass immediately by the use of force,
as when it protects a house from a mob by soldiers, or
appropriates private property to public use, or hangs a man in
pursuance of a judicial sentence, or whether it brings them about
mediately through men's fears, its object is equally an external
result. In directing itself against robbery or murder, for
instance, its purpose is to put a stop to the actual physical
taking and keeping of other men's goods, or the actual poisoning,
shooting, stabbing, and otherwise putting to death of other men.
If those things are not done, the law forbidding them is equally
satisfied, whatever the motive.