answerable for harm, unless he might have chosen otherwise. But
the choice must be made with a chance of contemplating the
consequence complained of, or else it has no bearing on
responsibility for that consequence. [55] If this were not true,
a man might be held answerable for everything which would not
have happened but for his choice at some past time. For instance,
for having in a fit fallen on a man, which he would not have done
had he not chosen to come to the city where he was taken ill.

All foresight of the future, all choice with regard to any
possible consequence of action, depends on what is known at the
moment of choosing. An act cannot be wrong, even when done under
circumstances in which it will be hurtful, unless those
circumstances are or ought to be known. A fear of punishment for
causing harm cannot work as a motive, unless the possibility of
harm may be foreseen. So far, then, as criminal liability is
founded upon wrong-doing in any sense, and so far as the threats
and punishments of the law are intended to deter men from
bringing about various harmful results, they must be confined to
cases where circumstances making the conduct dangerous were
known.

Still, in a more limited way, the same principle applies to
knowledge that applies to foresight. It is enough that such
circumstances were actually known as would have led a man of
common understanding to infer from them the rest of the group
making up the present state of things. For instance, if a workman
on a house-top at mid-day knows that the space below him is a
street in a great city, he knows facts from which a man of common
understanding would infer that there were people passing below.