Our Gemara on Amud Beis discusses the ethical and legal concept of a מִצְוָה לְקַיֵּים דִּבְרֵי הַמֵּת

It is a mitzvah to fulfill the directives of the dead. There are halakhic discussions over what extent it is legally binding, and under what circumstances, but there also seems to be some consensus that, regardless of the legality, there is a moral obligation to fulfill the wishes of the deceased. Why is this so?

There seems to be a tradition that as a person gets close to death one is able to achieve a level of prophecy because of the closeness of their soul to the next world. This is true for even a relatively average person, let alone a righteous person. (For some sources see Abravanel Devarim 33:3, and Sefer Chasidim 729.)

In fact, there seems to be a similar mystical tradition that we share with the ancient Greeks, or they intuited it on their own as well. In Socrates' closing speech to the people of Athens before he is unjustly executed (Plato’s Apology of Socrates, which we referred to in Psychology of the Daf Gittin 13), he states:

And now, O men who have condemned me, I would fain prophesy to you; for I am about to die, and that is the hour in which men are gifted with prophetic power.

The moral imperative to fulfill the wishes of the deceased, represents a textual problem for the Baale Tosafos (Paaneach Raza Vayishlach) regarding Yaakov’s changing Binyamin’s name.  We saw earlier in Psychology of the Daf Gittin 11 that Binyamin’s mother named him after the pain she went through, as an expression of sorrow, and perhaps also dedication and sacrifice. However, since his mother died during childbirth, his father re-purposed his name with a more optimistic connotation (Bereishis 15:18):

וַיְהִ֞י בְּצֵ֤את נַפְשָׁהּ֙ כִּ֣י מֵ֔תָה וַתִּקְרָ֥א שְׁמ֖וֹ בֶּן־אוֹנִ֑י וְאָבִ֖יו קָֽרָא־ל֥וֹ בִנְיָמִֽין׃

But as she breathed her last—for she was dying—she named him Ben-oni (son of my pain); but his father called him Benjamin (right-hand son).

Paaneach Raza asks how could Yaakov override the dying wishes of Rachel and use a different name?  Before we get to Paaneach Raza’s answer, I would like to explore a number of other answers, and why they are not necessarily viable. The simplest answer is that he did not override her wishes, but instead gave him an additional name. The fact that Paaneach Raza does not give this answer, is a proof that in ancient times they did not use multiple names. In fact, there is an interesting Teshuva of the Noda BeYehuda (II:OC:113) where he asserts that even in Talmudic times it was inappropriate to use multiple names. We might answer that since in general, a wife is supposed to defer to her husband, perhaps Yaakov is under no obligation to follow Rachel’s directive after death, any more than he is obligated when she is alive. But I would say that Paaneach Raza did not use this answer, because if it is, indeed, considered a prophecy, then this night trump ordinary everyday communication, and it is legitimate to wonder why Yaakov did not heed her words. 

Paaneach Raza answers that he only changed his name later in life to give recognition to the fact that, as his youngest son, he was his right-hand support in his old age. Another possible answer, though not given by the Paaneach Raza, is that since Yaakov’s chosen name was phonetically similar to Rachel’s chosen name, perhaps both her intention and his intention can be represented in the same name, and therefore not considered thwarting her wishes. If I am correct about this, there will be a halakhic outcome. Sometimes people want to name after a relative, but there are reasons why they cannot use that name so they use another name to symbolize the name. For example, when my son Hillel Eison was born, there was nobody yet named after my father’s father, Avraham. The reason for this is because my maternal grandfather’s name was also Avraham and he felt it was a bad sign to have somebody use his name while he was still alive. As a compromise, I gave my son the name Eison which is a Midrashic name for Avraham, as we say in the Yamim Noraim liturgy, עוד יזכר לנו אהבת איתן. In a similar vein, one might argue that if one name symbolically hints at the other, it is a sufficient expression of the name.