The talking snake vs. the talking donkey

I see that at YU Torah, there is a 15 minute shiur discussing:

A Snake Cannot Talk, But A Donkey Can? A Profound Lesson from the Abravanel

Speaker:Rabbi Hanan BalkGiven On:Sunday July 13, 2008

If I discussed this Abarbanel in this earlier post on parshas Bereishis. (And so did Rabbi Balk in an earlier shiur.) Just looking at the question, I intuited the answer that, it seems, Abarbanel explicitly states. But R' Balk develops this into a lesson on the boundaries of legitimate interpretation.

Here is the straightforward answer. In Bereishit, the Torah gives no indication that the snake talking is in any way out of the ordinary. Not only does Chava not react with shock, but there is no indication in the narrative itself that anything is strange. This seems problematic on a textual level, especially to a rationalist. However, the text itself in Balak notes that the donkey speaking is a strange occurrence. Thus, in Bemidbar 22:18:

28. The Lord opened the mouth of the she-donkey, and she said to Balaam, "What have I done to you that you have struck me these three times?"

כח. וַיִּפְתַּח ה אֶת פִּי הָאָתוֹן וַתֹּאמֶר לְבִלְעָם מֶה עָשִׂיתִי לְךָ כִּי הִכִּיתַנִי זֶה שָׁלֹשׁ רְגָלִים:

Thus, it is clear that absent God's opening the donkey's mouth, she would not have spoken. There is then not so much of a textual impetus, but rather just a rationalist impetus. This even though Bilaam does not react with shock at the talking donkey. That might be a result of his anger, or some aspect of the story left out.

Besides this, rationalists are not averse to accepting miracles, especially explicitly stated miracles. Thus, for example, even though Rabbi Yosef Ibn Caspi takes this all as a dream vision, following Rambam in Moreh Nevuchim in this, he is not averse to accepting it as literal truth if need be:

'Chai Hashem, I believe in all that is written in the Torah, and therefore I believe in the verse ותאמר האתון {in parashat Balak}, and in the verse וידבר חמור."