The standard thus adopted by the law is of necessity somewhat vague and indeterminate. It is not practicable to any great extent to lay down any more definite and detailed rules as to what classes of acts are negligent and what are not. Too much depends upon the circumstances of the individual case, and the standard of due care is too liable to alter with the advance of knowledge and the changes of social life and manners. Risks which were once deemed excessive may become permissible in view of the increasing stress and hurry of modern life, and conversely conduct which to-day is beyond reproach may in the future become grossly negligent by reason of the growth of skill or knowledge.
Nevertheless, here as elsewhere, the law seeks for definite and specific principles. It dislikes the licence of the arbitrium judicis. So far as practicable and justifiable it desires to make negligence a matter not of fact but of legal rule and definition. It seeks to supersede the vague principle that that is negligence which a jury considers such, by substituting for it a body of legal doctrine determining the boundaries of negligence in specific instances. This, however, is possible only to a very limited extent. It would seem, indeed, that all legal rules on this matter are merely negative, determining what does not amount to negligence, and never positive, determining that certain acts are negligent in law. It has been decided as a matter of law, for example, that it is not negligent to drive cattle through the streets of a town loose instead of leading them with halters.[[366]] Nor is it negligent to allow a dog to run at large, if the owner has no actual knowledge of its vicious temper. Nor is it negligent to try a horse for the first time in a frequented thoroughfare.[[367]] Nor is there any negligence in the usual practice of railway servants in violently shutting the doors of railway carriages without warning,[[368]] notwithstanding the risk of injury to the hands of passengers.[[369]]
As has been already indicated, there seem to be no corresponding rules to the effect that certain kinds of conduct are negligent in law. The law never goes further in this direction than to say that certain facts are sufficient evidence of negligence, that is to say, are sufficient to entitle the jury to find negligence as a matter of fact if they think fit. The reason for this cautious attitude of the law is obvious. No facts can be such cogent proof of negligence that the law may safely and wisely take them as conclusive. For they may be capable of explanation by other facts, and that which is apparently due to the most culpable negligence may be due in reality to inevitable mistake or accident. Thus the law does not contain any rule to the effect that driving on the wrong side of the road amounts to negligence. The rule is merely that such conduct is evidence of negligence.[[370]] Nor is the act of leaving a horse and cart unattended in the street an act of negligence in law; it is merely one from which a jury is at liberty to infer negligence in fact.[[371]]
§ 143. Degrees of Negligence.
We have said that English law recognises only one standard of care and therefore only one degree of negligence. Whenever a person is under a duty to take any care at all, he is bound to take that amount of it which is deemed reasonable under the circumstances, having regard to the ordinary practice of mankind; and the absence of this care is culpable negligence. Although this is probably a correct statement of English law, attempts have been made to establish two or even three distinct standards of care and degrees of negligence. Some authorities, for example, distinguish between gross negligence (culpa lata) and slight negligence (culpa levis), holding that a person is sometimes liable for the former only, and at other times even for the latter. In some cases we find even a threefold distinction maintained, negligence being either gross, ordinary, or slight.[[372]] These distinctions are based partly upon Roman law, and partly upon a misunderstanding of it, and notwithstanding some judicial dicta to the contrary we may say with some confidence that no such doctrine is known to the law of England.[[373]] These distinctions so drawn are hopelessly indeterminate and impracticable. On what principle are we to draw the line between gross negligence and slight? How can we thus elevate a distinction of degree into one of kind? Even were it possible to establish two or more standards, there seems no reason of justice or expediency for doing so. The single standard of English law is sufficient for all cases. Why should any man be required to show more care than is reasonable under the circumstances, or excused if he shows less?
In connection with this alleged distinction between gross and slight negligence it is necessary to consider the celebrated doctrine of Roman law to the effect that the former (culpa lata) is equivalent to wrongful intention (dolus)—a principle which receives occasional expression and recognition in English law also. Magna culpa dolus est,[[374]] said the Romans. In its literal interpretation, indeed, this is untrue, for we have already seen that the two forms of mens rea are wholly inconsistent with each other, and that no degree of carelessness can amount to design or purpose. Yet the proposition, though inaccurately expressed, has a true signification. Although real negligence, however gross, cannot amount to intention, alleged negligence may. Alleged negligence which, if real, would be exceedingly gross, is probably not negligence at all, but wrongful purpose. Its grossness raises a presumption against its reality. For we have seen that carelessness is measured by the magnitude and imminence of the threatened mischief. Now the greater and more imminent the mischief, the more probable is it that it is intended. Genuine indifference and carelessness is very unusual and unlikely in extreme cases. Men are often enough indifferent as to remote or unimportant dangers to which they expose others, but serious risks are commonly avoided by care unless the mischief is desired and intended. The probability of a result tends to prove intention and therefore to disprove negligence. If a new-born child is left to die from want of medical attention or nursing, it may be that its death is due to negligence only, but it is more probable that it is due to wrongful purpose and malice aforethought. He who strikes another on the head with an iron bar may have meant only to wound or stun, and not to kill him, but the probabilities are the other way. Every man is presumed to intend the natural and probable consequences of his acts,[[375]] and the more natural and probable the consequences, the greater the strength of the presumption.[[376]]
In certain cases this presumption of intent has hardened into a positive rule of law, and has become irrebuttable. In those cases that which is negligence in fact may be deemed wrongful intent in law. It is constructive, though not actual intent. The law of homicide supplies us with an illustration. Murder is wilful homicide, and manslaughter is negligent homicide, but the boundary line as drawn by the law is not fully coincident with that which exists in fact. Much that is merely negligent in fact is treated as wilful homicide in law. An intent to cause grievous bodily harm is imputed as an intent to kill, if death ensues, and an act done with knowledge that it will probably cause death is in law an act done with intent to cause it.[[377]] The justification of such conclusive presumptions of intent is twofold. In the first place, as already indicated, very gross negligence is probably in truth not negligence at all, but wrongful purpose; and in the second place, even if it is truly negligence, yet by reason of its grossness it is as bad as intent, in point of moral deserts, and therefore may justly be treated and punished as if it were intent. The law, accordingly, will sometimes say to a defendant: “Perhaps, as you allege, you were merely negligent, and had no actual wrongful purpose; nevertheless you will be dealt with just as if you had, and it will be conclusively presumed against you that your act was wilful. For your deserts are no better than if you had in truth intended the mischief which you have so recklessly caused. Moreover it is exceedingly probable, notwithstanding your disclaimer, that you did indeed intend it; therefore no endeavour will be made on your behalf to discover whether you did or not.”
§ 144. Other Theories of Negligence.
The analysis of the conception of negligence is a matter of some considerable difficulty, and it is advisable to take account of certain theories which differ more or less seriously from that which has been here accepted by us.
It is held by some, that negligence consists essentially in inadvertence. It consists, that is to say, in a failure to be alert, circumspect, or vigilant, whereby the true nature, circumstances, and consequences of a man’s acts are prevented from being present in his consciousness. The wilful wrongdoer is lie who knows that his act is wrong; the negligent wrongdoer is he who does not know it, but would have known it, were it not for his mental indolence.[[378]]