In this week’s parshah, we learn that when a person dies he conveys tumah. There is a machlokes why that is the case.
The Ramban, in the beginning of this week’s parshah, explains that when a person dies by means of the malach hamaves (angel of death) he conveys tumah. However, if he dies by means of neshikah (a form of death performed by Hashem) he isn’t. This is why Chazal said that tzaddikim do not become tamei upon death, since presumably they die by means of neshikah.
The Avnei Neizer (Yoreh De’ah 466) adds that Rav Chayim Vital says that the malach hamaves sprinkles three bitter drops on a person when he comes to kill him – and those drops create the tumah.
The Ohr HaChayim has a different understanding of why a dead person becomes tamei. He explains that since we accepted the Torah, we possess a high level of kedushah, and the forces of tumah are constantly anticipating and eagerly awaiting a chance to cling to this kedushah. As soon as a Jew dies the forces of tumah are able to enter his body, and thus he becomes tamei. This explanation, he says, also accounts for why a non-Jew does not become tamei upon death; since in his life he didn’t possess this kedushah, the forces of tumah are not interested in entering his body.
The Ohr HaChayim explains that with this understanding we can answer the following question pertaining to the words at the beginning of Parshas Chukas, “Zos chukas haTorah”: Why does the Torah refer to the mitzvah of tumah as “the chok of the Torah”? It does so, explains the Ohr HaChayim, because tumah only rests on deceased Jews due to them having accepted the Torah.
The Zohar says that only someone who dies of natural causes was killed by the malach hamaves. People who are killed by others were not killed by the malach hamaves. Based on this, the Avnei Neizer says there is a halachic ramification to the dispute between the Ramban and the Ohr HaChayim. According to the Ramban who said tumah sets in only when the malach hamaves kills, one killed by another does not become tamei. However, according to the Ohr HaChayim even one who is killed by another does become tamei.
It is unclear if graves of tzaddikim convey tumah and consequently whether a kohen can visit them. Even according to the Ramban’s opinion – that a dead person only conveys tumah when the malach hamaves kills him – tzaddikim still may convey tumah when they die since many tzaddikim die by means of the malach hamaves and not via neshikah. And even according to the Or HaChayim’s view – that tumah sets in due to the sudden absence of kedushah – a tzaddik perhaps doesn’t convey tumah since his body actually became kadosh during his lifetime, and it remains kadosh after his death.
Tosafos (on Baba Metzia 114b) cites a Medrash Yalkut in Mishlei that relates that when Eliyahu HaNavi and Rabbi Yehoshua (a talmid of Rabbi Akiva) were burying Rabbi Akiva, Rabbi Yehoshua asked Eliyahu HaNavi how he, as a kohen, could bury a dead person. Eliyahu HaNavi answered that talmidei chachamim and their talmidim do not convey tumah. Tosafos says that Eliyahu HaNavi gave this answer out of respect for Rabbi Akiva. The actual reason he was allowed to bury Rabbi Akiva was because Rabbi Akiva was murdered by the government and no one was willing to bury him; thus, he had the status of a meis mitzvah for whom a kohen is allowed to become tamei. Apparently Tosafos maintains that tzaddikim convey tumah.