The Talmud understands from the double language of “v’rapo y’rape” (Shemot 21:19) that “permission is given to the doctor (ropheh) to heal. This view is quoted in Shulchan Arukh (Y.D. 336:1) where it is noted that medical care is not only permitted, but a mitzvah (see Rosh and Ran, Nedarim 41a). (See Resp. S’deh Elchanan, I, 60, who discusses the obligation to heal when the patient is unwilling, and must be deceived.)

There is some discussion as to what exactly would have been prohibited so that permission would be needed. There are at least two basic approaches to this question (see Ramban, Vayikra 26:11). One approach is that the concern is philosophical; perhaps when someone is sick, that is considered G-d’s will, and it is wrong to interfere with that. This perspective is relayed by Toasfot (Bava Kama 85a, s.v. sh’nitnah) who explain that the double language is necessary to teach that this concern is inapplicable whether the affliction was natural in origin or inflicted by man.

The second approach is more practical: engaging in medical procedures involves a risk of causing further damage. Perhaps that risk is not justified, and perhaps it places a liability upon the practicioner. Thus, permission and license is needed. This attitude is expressed by the Shach (Y.D. 336:1; see Tosefta, Bava Kama 6:6) who interprets the Talmud’s point: “So one should not say, why do I need this trouble, perhaps I will err, and be found an inadvertent murderer?” (See Resp. Shraga HaMeir, VI, 73:4).

The second concern does maintain some impact on halakhah in the need for doctors to be properly qualified. (See Y.D. 336:1) The rules applicable to a doctor who errs and causes damage, if the error is a function of negligence, are complex and analyzed by poskim (see Resp. Tashbetz, III, 82; Birkei Yosef Y.D. 336:4-8; Mishpetei haTorah, I, 12).

The Ibn Ezra in his commentary makes a distinction in the permission to heal between internal and external injuries. R. Simcha Z. Broide (Sam Derekh to Shemot) suggests the Ibn Ezra is working with the second approach discussed above, and is thus concerned that the limited access to information about the injury would bring a greater likelihood of error, and thus the risk is too great. While in general the Ibn Ezra’s distinction is not accepted, some poskim did consider it to have some relevance in indicating limited authority to doctors in circumstances where they are unable to actually confront the wound directly (see Kreiti, Y.D. 188:5, and Resp. L’Horot Natan, V, 115:9).