§ 141. Objection Considered.
By way of objection to the foregoing analysis it may be said: “It is not true that in all cases negligence amounts to carelessness in the sense of indifference. A drunken man is liable for negligence if he stumbles as he walks along the street, and breaks a shop window, but he may have been exceedingly anxious to walk in a straight line and to avoid any such accident. He may have been conscientiously using his best endeavours, but they will not serve to justify him on a charge of negligence. So an unskilful physician may devote to the treatment and cure of his patient an amount of anxious attention and strenuous endeavour, far in excess of that which one more skilful would consider necessary; yet if his treatment is wrong, he is guilty of negligence.”
The answer to this objection is that in these and all similar cases carelessness in the sense of indifference is really present, though it is remote instead of immediate. The drunken man may be anxious and careful now not to break other persons’ windows, but if he had been sufficiently anxious and careful on the point some time ago, he would have remained sober, and the accident would not have happened. So with the unskilful physician. It is a settled principle of law that want of skill or of professional competence amounts to negligence. Imperitia culpae adnumeratur.[[363]] He who will exercise any trade or profession must bring to the exercise of it such a measure of skill and knowledge as will suffice for reasonable efficiency, and he who has less than this practises at his own risk. The ignorant physician who kills his patient, or the unskilful blacksmith who lames the horse shod by him, is legally responsible, not because he is ignorant or unskilful—for skill and knowledge may be beyond his reach—but because, being unskilful or ignorant, he ventures to undertake a business which calls for qualities which he does not possess. No man is bound in law to be a good surgeon or a capable attorney, but all men are bound not to act as surgeons or attorneys until and unless they are good and capable as such.
The unskilful physician, therefore, is liable not because he is now careless of the health of his patient, but because he was formerly careless in undertaking work calling for greater skill than he possessed. If he then knew that he had not the requisite skill, his carelessness is obvious. Possibly, however, he believed himself to be sufficiently qualified. In this case we must go one step further back in the search for that mental attitude of indifference which is the essential element in all cases of negligence. He was careless in forming his beliefs; he formed them without that anxious consideration which the law requires from those who form beliefs on which they act to the injury of others. A man may be called upon by the law to answer to-day for the carelessness with which he formed an opinion years ago.
§ 142. The Standard of Care.
Carelessness is not culpable, or a ground of legal liability, save in those cases in which the law has imposed a duty of carefulness. In all other cases complete indifference as to the interests of others is allowable. No general principle can be laid down, however, with regard to the existence of this duty, for this is a matter pertaining to the details of the concrete legal system, and not to abstract theory. Carelessness is lawful or unlawful, as the law sees fit to provide. In the criminal law liability for negligence is quite exceptional. Speaking generally, crimes are wilful wrongs, the alternative form of mens rea being deemed an insufficient ground for the rigour of criminal justice. This, however, is not invariably the case, negligent homicide, for example, being a criminal offence. In the civil law, on the other hand, no such distinction is commonly drawn between the two forms of mens rea. In general we may say that whenever an act would be a civil wrong if done intentionally, it is also a civil wrong if done negligently. When there is a legal duty not to do a thing on purpose, there is commonly a legal duty to take care not to do it accidentally. To this rule, however, there are certain exceptions—instances in which wrongful intent is the necessary basis even of civil liability. In these cases a person is civilly responsible for doing harm wilfully, but is not bound to take any care not to do it. He must not, for example, deceive another by any wilful falsehood, but unless there is some special ground of obligation in the case, he is not answerable for false statements which he honestly believes to be true, however negligent he may be in making them.[[364]] Other instances of the same sort are based upon the express or implied agreement or understanding of the persons concerned. Thus the gratuitous lender of a chattel is bound to disclose any dangerous defects which he actually knows of, but is not bound to take any care whatever to see that it is safe, or to discover and disclose defects of which he is ignorant. For he who borrows a thing gratuitously agrees impliedly to take it as it is, and to run all risks. But he who hires a thing for money is entitled to the exercise of due care for his safety on the part of the owner.[[365]]
Carelessness may exist in any degree, and in this respect it differs from the other form of mens rea. Intention either exists or it does not; there can be no question of the degree in which it is present. The degree of carelessness varies directly with the risk to which other persons are exposed by the act in question. He is careless, who, without intending evil, nevertheless exposes others to the danger of it, and the greater the danger the greater the carelessness. The risk depends, in its turn, on two things: first, the magnitude of the threatened evil, and second, the probability of it. The greater the evil is, and the nearer it is, the greater is the indifference or carelessness of him who creates the danger.
Inasmuch, therefore, as carelessness varies in degree, it is necessary to know what degree of it is requisite to constitute culpable negligence. What measure of care does the law demand? What amount of anxious consideration for the interests of others is a legal duty, and within what limits is indifference lawful?
We have first to notice a possible standard of care which the law might have adopted but has not. It does not demand the highest degree of care of which human nature is capable. I am not liable for harm ignorantly done by me, merely because by some conceivable exercise of prudential foresight I might have anticipated the event and so avoided it. Nor am I liable because, knowing the possibility of harm, I fail to take every possible precaution against it. The law demands not that which is possible, but that which is reasonable in view of the magnitude of the risk. Were men to act on any other principle than this, excess of caution would paralyse the business of the world. The law, therefore, allows every man to expose his fellows to a certain measure of risk, and to do so even with full knowledge. If an explosion occurs in my powder mill, I am not liable for negligence, even though I established and carried on the industry with full knowledge of its dangerous character. This is a degree of indifference to the safety of other men’s lives and property which the law deems permissible because not excessive. Inasmuch as the carrying of firearms and the driving of horses are known to be the occasions of frequent harm, extreme care and the most scrupulous anxiety as to the interests of others would prompt a man to abstain from those dangerous forms of activity. Yet it is expedient in the public interest that those activities should go on, and therefore that men should be exposed to the incidental risks of them. Consequently the law does not insist on any standard of care which would include them within the limits of culpable negligence. It is for the law to draw the line as best it can, so that while prohibiting unreasonable carelessness, it does not at the same time demand unreasonable care.
What standard, then, does the law actually adopt? It demands the amount of care which would be shown in the circumstances of the particular case by an ordinarily careful man. It is content to adopt the standard which is customary for the time being in the community. It is satisfied with conduct which in point of carefulness conforms to the moral standard and the ordinary practice of mankind. Less than this is not sufficient, and more than this is not required. A jury in determining the question of negligence will decide whether in their opinion the defendant acted with reasonable care; and in so doing they represent and express the current opinion and practice of the community as to the risks to which one man is justified in exposing others, and as to the degree of consideration for the welfare of others which the community exacts and commonly receives from its members.