Whether this strict rule is based on the common grounds of liability, or upon some special consideration of past or present policy, policy has set some limits to it, as was mentioned in the foregoing Lecture.

Another case of conduct which is at the risk of the party without further knowledge than it necessarily imports, is the keeping of a tiger or bear, or other animal of a species commonly known to be ferocious.  If such an animal escapes and does damage, the owner is liable simply on proof that he kept it.  In this instance the comparative remoteness of the moment of choice in the line of causation from the effect complained of, will be particularly noticed.  Ordinary cases of liability arise out of a choice which was the proximate cause of the harm upon which the action is founded.  But here there is usually no question of negligence in guarding the beast.  It is enough in most, if not in all cases, that the owner has chosen to keep it.  Experience has shown that tigers and bears are alert to find means of escape, and that, if they escape, they are very certain to do harm of a serious nature.  The possibility of a great danger has the same effect as the probability of a less one, and the law throws the risk of [155] the venture on the person who introduces the peril into the community.

This remoteness of the opportunity of choice goes far to show that this risk is thrown upon the owner for other reasons than the ordinary one of imprudent conduct.  It has been suggested that the liability stood upon remote inadvertence. 1 But the law does not forbid a man to keep a menagerie, or deem it in any way blameworthy.  It has applied nearly as strict a rule to dealings which are even more clearly beneficial to the community than a show of wild beasts.

This seems to be one of those cases where the ground of liability is to be sought in policy coupled with tradition, rather than in any form of blameworthiness, or the existence of such a chance to avoid doing the harm as a man is usually allowed.  But the fact that remote inadvertence has been suggested for an explanation illustrates what has been said about the difficulty of deciding whether a given rule is founded on special grounds, or has been worked out within the sphere of negligence, when once a special rule has been laid down.

It is further to be noticed that there is no question of the defendant’s knowledge of the nature of tigers, although without that knowledge he cannot be said to have intelligently chosen to subject the community to danger.  Here again even in the domain of knowledge the law applies its principle of averages.  The fact that tigers and bears are dangerous is so generally known, that a man who keeps them is presumed to know their peculiarities.  In other words, he does actually know that he has an animal with certain teeth, claws, and so forth, and he must find out the [156] rest of what an average member of the community would know, at his peril.