1) DO THE DEAD KNOW WHAT IS HAPPENING IN THIS WORLD?
QUESTION: At the end of a lengthy discussion as to whether the dead are aware of the happenings in this world, the Gemara (18b) concludes that even Rebbi Yonasan (who, on 18a, asserted that the dead do not know what is happening in this world) changed his mind and said that the dead do know what is happening. He derived this from a verse that says that Hash-m told Moshe Rabeinu to relate to the deceased forefathers, Avraham, Yitzchak, and Yakov, that the Jewish people had entered Eretz Yisrael. The Gemara concludes that the dead must be aware of what is happening in this world, because "if they do not know, then what good will it do [for Moshe Rabeinu] to tell them?"
From this Gemara it seems that if the dead do not know what is happening in this world, then even when someone tells them about something in this world, they do not know what is happening. They have absolutely no awareness of anything this-worldly. As Rashi (DH v'Iy) notes, the basis for the Gemara's question is the assumption that the dead "do not understand anything other than the pain that they bear."
This Gemara is difficult to understand, because the Gemara earlier (18b) implies that when the dead are informed, they do know what is happening. The Gemara there never mentions the possibility that they are so removed from this world that they have no idea what is happening even when they are told! (MAHARSHA)
(a) The MAHARSHA answers that the Gemara here is addressing Rebbi Yonasan's opinion. Earlier (18a), Rebbi Yonasan cited the verse, "The dead people do not know anything" (Koheles 9:5). This implies that Rebbi Yonasan was of the opinion that the dead have absolutely no awareness of anything this-worldly, even when they are informed of it.
When the Gemara (on 18b) says that the dead do know what is happening in the world when someone informs them, it is responding to one of Rebbi Chiya's sons who asserted that his father does not know of their pain. The Gemara is saying that even if the dead generally do not know what is happening of their own accord, they could know if they were to be informed.
(b) For what purpose did Hash-m command Moshe Rabeinu to tell the forefathers about the Jewish people's entry into Eretz Yisrael? It must have been so that the forefathers would continue to watch their children and pray for them when they would wage war and conquer the land. The Gemara asks that if dead people do not know what is happening in the world, then what good would it do for Moshe Rabeinu to tell them? While they might be aware of the events of the world when they are informed of them, Moshe Rabeinu could not tell them exactly when the Jews would go to war and when to pray for them, because Moshe himself would not know when that was! (M. KORNFELD)
This explanation is consistent with the reading of the text that Tosfos (Sotah 34b, DH Avosai) has in our Gemara. In Tosfos' text, the word "Ela" ("rather") appears before the Gemara's answer, "So that they would express gratitude to Moshe." According to Tosfos, this answer is not addressing the question that immediately precedes it ("If they know [what is happening in the world], then what is the point in telling them [what is happening]?"), but rather it is answering the first question, "If they do not know [what is happening in the world], then what is the point in telling them [what is happening]?" (See GILYON HA'SHAS to 18b, and DIKDUKEI SOFRIM here, footnote #8.) The Gemara is answering that the point in telling them is so that they would appreciate what Moshe Rabeinu did for their children from the time that they left Egypt until the nation entered Eretz Yisrael (and not so that they could pray for their children in the future).
According to the Maharsha's explanation, this reading of the Gemara is not plausible. The Maharsha explains that if they do not know what is happening, then they have absolutely no understanding of anything this-worldly, and thus they could not even be grateful to Moshe Rabeinu for bringing the Jews to Eretz Yisrael.
2) TRANSGRESSING THE TORAH FOR THE SAKE OF MAN'S HONOR
QUESTION: The Gemara says that if one finds Sha'atnez in his garment, he must remove his garment immediately, even if he is in a public place and will be embarrassed. One may not transgress a Mitzvah for the sake of his honor.
The Gemara concludes (on 20a) that man's honor does not override the Mitzvos of the Torah only when one is actively transgressing a Torah prohibition. One who is wearing Sha'atnez is actively violating the prohibition of Sha'atnez. However, one may transgress the Torah passively in order to prevent disgrace. The Gemara learns this from the law of Mes Mitzvah. When there is a corpse that needs to be buried, one may bury the corpse even if he thereby will forgo the Mitzvah of offering the Korban Pesach or circumcising his son.
RASHI (20a, DH Shev v'Al Ta'aseh) cites the Gemara in Yevamos (90b) which teaches that the Rabanan have the authority to instruct us to violate a Mitzvah in a passive manner. For example, the Rabanan command us not to put Tzitzis on a four-cornered, linen garment, even though mid'Oraisa such a garment is required to have Tzitzis. Since one will only be passively violating the Torah's command, the Rabanan have the authority to make such an enactment.
TOSFOS (Yevamos 90b, DH Kulhu Nami) questions how wearing a four-cornered garment without Tzitzis can be considered a passive infraction. Wearing a garment without Tzitzis should be considered an active transgression of the Torah's command not to don a four-cornered garment without Tzitzis, just as wearing a garment that is Sha'atnez is an active transgression of the Torah's command not to wear Sha'atnez!
ANSWER: TOSFOS answers that the Torah commands a person to attach Tzitzis only to a four-cornered garment that he is wearing. The obligation of Tzitzis takes effect only a moment after donning the garment. At that point (once the garment has already been put on), the person is passively wearing a garment without Tzitzis.
The Gemara concludes that wearing a garment with Sha'atnez is indeed an active transgression because the prohibition of wearing Sha'atnez includes the prohibition to place the garment on oneself. Although now -- while wearing the garment -- one is transgressing only passively, since he initially transgressed the prohibition in an active manner he is required to remove it immediately. (Alternatively, since he initially transgressed the prohibition actively, as long as the garment remains on him, he is considered to be actively transgressing the prohibition of Sha'atnez.)
The SHA'AGAS ARYEH (#82) and NODA B'YEHUDAH (EH 2:141) point out that there is a problem with this explanation. The Torah permits one to attach woolen Tzitzis to a linen garment because the Mitzvah of Tzitzis overrides the prohibition of Sha'atnez. Why, though, is one permitted to put on such a garment? The very moment that he dons the garment, he transgresses the prohibition of Sha'atnez, and the Mitzvah of wearing Tzitzis (which would override the prohibition of Sha'atnez) takes effect only a moment later, when the garment is already resting on his body!
The Sha'agas Aryeh leaves this question unanswered. The Noda b'Yehudah, though, answers that Tosfos may rule like the NEMUKEI YOSEF in Bava Metzia (30a), who says that if a Mitzvas Aseh is accomplished by performing a certain act, any unavoidable preparations that lead up to, and form the beginning of, that act also override a Torah prohibition. Since it is impossible to wear the Tzitzis without first putting on the garment, putting it on also overrides the prohibition of Sha'atnez.