Whom Do We Trust?

Abaye responded and said: One should not say this, as it was taught in the school of Rabbi Yishmael that from the verse, “And shall cause him to be thoroughly healed” (Exodus 21:19), from here we derive that permission is granted to a doctor to heal. The practice of medicine is in accordance with the will of God.

The Torah has granted the physician permission to heal, and it is a religious duty which comes under the rule of saving an endangered life. If he withholds [treatment] he is regarded as one who sheds blood; and even if there is someone else who can heal him; for not from every one does one merit to be healed. Nevertheless, one should not occupy himself with medical treatment unless he is an expert and there is none other greater than he; for if not so, he is regarded as one who sheds blood. If one administered medical treatment without the permission of the Jewish Court, he is subject to payment of indemnities, even if he is an expert; and if he administered medical treatment, having the permission of the Jewish Court, and erred, causing [thereby] injury [to the patient], he is exempt by the laws of man and is held responsible by the laws of Heaven. If he caused death and it became known to him that he acted inadvertently, he is banished on account of him.

There is an opinion (RAMBAM, Yad, Shevitat Assor 2:8) that argues that where the Mishnah says that we listen to the experts, that means a reputable and knowledgeable expert, as opposed to doctors who are not so wise or expert. This seems an unlikely view, for we do not find that courts rule according to the wisest opinion but by the majority opinion. It is true that we find (BT Avodah Zarah 7a) that where rabbinical opinion is divided, one ruling pure and one ruling impure, or one permitting and one forbidding, if one rabbi is wiser than the other his opinion prevails, and therefore where medical opinion is equally divided we do take the more wise and expert opinion. In the situation of the law-court, although in principle we require consensus before ruling, all the judges present are required to express an opinion and the Torah stipulated that the majority decides. But here [in medical issues] we listen to the expert, and there is no reason to seek a second opinion from a lesser expert - his opinion would be void. However, where two doctors are opposed by one, since they are all equally competent professionals, the single opinion cannot prevail. Nonetheless, if one of them is exceptionally wise we do prefer his opinion even if he is a small minority. This is true in order to enable the patient to eat, but if he says the patient does not need to eat where other less expert doctors say he needs to eat, he is considered as a lone voice and is not heeded. There is a source for this (BT Yevamot 14a) in the dispute between the schools of Shammai and Hillel where the school of Shammai is the more convincing. We rule that the majority opinion applies where the opposing opinions are of equal authority, but nonetheless we take the wiser and more expert opinion in order to rule more strictly. In our context the "stricter" ruling means leniency [with the Yom Kippur fast] in cases of medical danger, allowing you to supply the patient with all he needs.

Abba Guryan of Tzadyan says in the name of Abba Gurya: A person may not teach his son the trades of a donkey driver, a camel driver, a pot maker, a sailor, a shepherd, or a storekeeper. The reason for all these is the same, as their trades are the trades of robbers; all of these professions involve a measure of dishonesty and are likely to lead to robbery. Rabbi Yehuda says in Abba Gurya’s name: Most donkey drivers are wicked, since they engage in deceit, and most camel drivers, who traverse dangerous places such as deserts, are of fit character, as they pray to God to protect them on their journeys. Most sailors are pious, since the great danger of the seas instills in them the fear of Heaven. The best of doctors is to Gehenna, and even the fittest of butchers is a partner of Amalek.

This requirement applies to a roof, and similarly, to any place that might present a danger and cause a person to stumble and die. For example, if a person has a well or a cistern in his courtyard, he must erect a sand wall ten handbreadths high around them or make a cover for them, so that a person will not fall in and die.
Similarly, it is a positive mitzvah to remove any obstacle that could pose a danger to life, and to be very careful regarding these matters, as Deuteronomy 4:9 states: "Beware for yourself; and guard your soul." If a person leaves a dangerous obstacle and does not remove it, he negates the observance of a positive commandment, and violates the negative commandment: "Do not cause blood to be spilled."