The theory of torts may be summed up very simply.  At the two extremes of the law are rules determined by policy without reference of any kind to morality.  Certain harms a man may inflict even wickedly; for certain others he must answer, although his conduct has been prudent and beneficial to the community.

But in the main the law started from those intentional wrongs which are the simplest and most pronounced cases, as well as the nearest to the feeling of revenge which leads to self-redress.  It thus naturally adopted the vocabulary, [162] and in some degree the tests, of morals.  But as the law has grown, even when its standards have continued to model themselves upon those of morality, they have necessarily become external, because they have considered, not the actual condition of the particular defendant, but whether his conduct would have been wrong in the fair average member of the community, whom he is expected to equal at his peril.

In general, this question will be determined by considering the degree of danger attending the act or conduct under the known circumstances.  If there is danger that harm to another will follow, the act is generally wrong in the sense of the law.

But in some cases the defendant’s conduct may not have been morally wrong, and yet he may have chosen to inflict the harm, as where he has acted in fear of his life.  In such cases he will be liable, or not, according as the law makes moral blameworthiness, within the limits explained above, the ground of liability, or deems it sufficient if the defendant has had reasonable warning of danger before acting.  This distinction, however, is generally unimportant, and the known tendency of the act under the known circumstances to do harm may be accepted as the general test of conduct.

The tendency of a given act to cause harm under given circumstances must be determined by experience.  And experience either at first hand or through the voice of the jury is continually working out concrete rules, which in form are still more external and still more remote from a reference to the moral condition of the defendant, than even the test of the prudent man which makes the first stage of the division between law and morals.  It does this in the domain [163] of wrongs described as intentional, as systematically as in those styled unintentional or negligent.

But while the law is thus continually adding to its specific rules, it does not adopt the coarse and impolitic principle that a man acts always at his peril.  On the contrary, its concrete rules, as well as the general questions addressed to the jury, show that the defendant must have had at least a fair chance of avoiding the infliction of harm before he becomes answerable for such a consequence of his conduct.  And it is certainly arguable that even a fair chance to avoid bringing harm to pass is not sufficient to throw upon a person the peril of his conduct, unless, judged by average standards, he is also to blame for what he does.