How is our Gemara consistent with the story in Kidushin (I think 39(b)) that Acher went off the path because of what he saw happen to Chutzpis Hamiturgiman (by the Asarah Harugei Malchus)?
Tosfos here cites the Yerushalmi which also mentions an incident similar to that recorded in Kidushin (39b). The Yerushalmi mentions two opinions: (1) Acher saw a person fulfilling the request of his father (the Mitzvah of Kibud Av) by sending away the mother bird in order to take the chicks (the Mitzvah of Shilu'ach ha'Ken); (2) Acher saw the tongue of Rebbi Yehudah ha'Nachtum being draged by a dog. Tosfos refers to the Gemara in Kidushin.
Regarding the apparent contradiction between our Gemara, which says that Acher saw a Malach sitting down in the heavens, or that "Greek tunes never ceased from his mouth" and "heretical books fell from his lap when he would arise from the Beis Midrash," and the sources in the Yerushalmi and in Kidushin for why Acher went off the path, it seems that there is no contradiction at all. Rather, the Gemara means that Acher's entire service of Hash-m was done on condition to receive reward (such as honor, as mentioned in Tosfos), and thus essentially he was a Ba'al Ta'avah learning Torah only for the sake of obtaining pleasure in this world. The idea behind constantly singing of Greek song is trying to make the most out of this world. The two incidents in the Yerushalmi and in Kidushin express this nature of Acher, for when he saw that servants of Hash-m met with such terrible fates in this world , that contradicted his concept of serving Hash-m in order to receive reward in this world and the dissonance caused him to go bad.
It might have been the heretical books that he was reading about Greek philosophy which denied the existence of Olam ha'Ba that brought him to seek reward in this world. When he saw the Malach sitting down he became convinced that there are two powers that control the world, one of good and one of evil (as was the common notion in those days among the Nochrim), and that brought him to the erroneous conclusion that the power of evil is able to cause misfortune to befall a Tzadik, and through this he came to complete heresy.
Thus, it was a combination of all of these incidents that caused Acher to go bad "Ha v'Ha Garma."
Mordecai Kornfeld
Rather, the Gemara means that Acher's entire service of
Hash-m was done on condition to receive reward (such as honor, as
mentioned in Tosfos), and thus essentially he was a Ba'al Ta'avah learning Torah only for the sake of obtaining pleasure in this world. The idea behind constantly singing of Greek song is trying to make the most out of this world. The two incidents in the Yerushalmi and in Kidushin express this nature of Acher, for
when he saw that servants of Hash-m met with such terrible fates in this world, that contradicted his concept of serving Hash-m in order to receive reward in this world and the dissonance caused him to go bad.
While Ein Mshivin Al Hadrush, Tos. is referring to his father, and in our Gemara it says that he said "Hoil Vitrid...Mhahu Almoh" prior to that he may not have been interested in Tavos Olom Hazeh.
Kol Tuv
Yitzchok Zirkind
Certainly he was affected by the Chinuch he received from his father. And from what he said at the end -- that he wanted to get pleasure from this world -- we see that that was his intention all along (as the Gemara says on 14b, "Tina Haysah b'Libam").
In the Insights we discussed this at length, and we cited a proof for this from Kidushin (39b), where the Gemara says that when Acher saw that there is no S'char in this world, it brought him to Kefirah.
Mordecai Kornfeld