What happens when the neshama has an aliya?

Question

there is a common practice to learn torah for someone who is deceased 'l'iluy nishmato/a' - to raise her/his soul. There is also a common (american/ashkenazik?) custom for a relative of a deceased person to provide food and drink to others on the yartzeit of the deceased. Before making a blessing on the food and drink (or sometimes after) people will say "the neshama should have an aliya".

I would like to understand the mechanics of what is happening here. presumably the miztvot that are being done accrue some sort of merit for the deceased person. Is this correct?

I also assume that these merits cause the neshama to become closer to God which is what is implied by 'having an aliya'. How is this understood; especially in light of the Rambam's statement that a person's closeness to God is directly proportionate to the person's intellectual grasp of God

Answer 1

R. Hai Gaon has a respnsum about how the actions of the living can impact the dead. While he first notes the possibility that certain things can be done to relieve the punishment of the dead, he concludes the responsum by asserting that there is absolutely nothing anyone can do to increase the dead's merit and earn him more reward. The dead's level and the extent of his "pleasure" from basking in the glory of the Shechina are determined solely by his own actions while alive.

Otzar HaGaonim Chagigah p. 27-28

ולזכותו למתן שכר אין ביד אדם כל עיקר ואין מעלתו וגדולתו והנאתו מזיו השכינה אלא לפי מעשיו ואפילו כל צדיקי עולם בקשו עליו רחמים וכל צדקות נעשו לזכותו אין מועילין לו בזאת

This responsum is summarized in English by R. Louis Jacobs.

Theology in the Responsa p. 21

All this concerns punishment alone. The reward of enjoying the radiance of the Divine Presence in the Hereafter can be attained only through deeds a man performs himself while alive on earth. For a man to attain to this sublime bliss it can avail him nothing even if all the good men on earth carry out virtuous deeds on his behalf.

Answer 2

Rav Matesyahu Solomon explains in the name of Rabbi Eliyahu Lopian the efficacy of praying for others such: When a person causes others to pray for him (by being sick, for example), he becomes like their teacher in that he causes them to do good.

The same principle can apply to a deceased person. A person's children's and students' deeds performed AS A RESULT OF HIS INSTRUCTIONS do continue to cause his neshama to be raised in Gan Eden (the commentators explain that this is why there is a final judgement day at the end of days. Although the deceased have been judged upon their death, at the end of days the full consequences of their actions will become clear.) So when one performs a mitzvah that would not have been done otherwise because of the deceased, the deceased acquires the merit of causing their good deed and hence receives additional reward ("rises").