As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school, which bases its tenets on the doctrines laid out in the Brahma Sutras, a work by the sage Vyasa that summarizes and systematizes the philosophical teachings of the Upanishads. You can read the Brahma Sutras here. In any case, in Adhyaya 3 Pada 3 of the Brahma Sutras, Vyasa says this:
- eka ātmanaḥ śarīre bhāvāt
Some deny the existence of the soul, its existence being dependent on the existence of the body.
- vyatirekastadbhāvabhāvitvānna tūpalabdhivat
But this is not so; there is a distinction (between the soul and the body) because consciousness may not exist even when the body exists, as it is in the case of perception.
This translation is written from the viewpoint of the Advaita philosopher Adi Shankaracharya, who believes that in these Sutras Vyasa is demonstrating that there exists a soul which is different from the body. Now in this section of Adi Shankaracharya's Brahma Sutra Bhashya, a hypothetical opponent raises the objection that it's improper for Vyasa to discuss this subject, because it was already discussed in the Purva Mimamsa Sutras. As I discuss in this question, Jaimini's Purva Mimamsa Sutras and Vyasa's Brahma Sutras originally formed a unified Mimamsa Shastra, so it would be like discussing the same subject twice in the same work. But Adi Shankaracharya responds by saying that the existence of the soul is only discussed in a commentary on the Purva Mimamsa Sutras, not in the text itself, and so it's fine for Vyasa to discuss it in the Brahma Sutras:
But, an objection is raised, already in the first pâda which stands at the head of this Sâstra (i.e. the first pâda of the Pûrva Mîmâmsâ-sûtras) there has been declared the existence of a Self which is different from the body and hence capable of enjoying the fruits taught by the Sâstra.--True, this has been declared there by the author of the bhâshya, but there is in that place no Sûtra about the existence of the Self. Here, on the other hand, the Sûtrakâra himself establishes the existence of the Self after having disposed of a preliminary objection. And from hence the teacher Sabara Svâmin has taken the matter for his discussion of the point in the chapter treating of the means of right knowledge. For the same reason the reverend Upavarsha remarks in the first tantra--where an opportunity offers itself for the discussion of the existence of the Self--'We will discuss this in the Sârîraka,' and allows the matter to rest there. Here, where we are engaged in an inquiry into the pious meditations which are matter of injunction, a discussion of the existence of the Self is introduced in order to show that the whole Sâstra depends thereon.
I discuss the statement about Upavarsha in my question here. But now I'm interested in the statement in bold. Let me explain what Adi Shankaracharya is saying. Shabara Swami's Mimamsa Sutra Bhashya is the canonical commentary on Jaimini's Purva Mimamsa Sutras. In this excerpt from his commentary on Adhyaya 1 Pada 1 Sutra 5 of the Purva Mimamsa Sutras, Shabara Swami presents an argument for the existence of the soul, which he needs to establish because he's trying to show that Yagnas which bear fruit in the afterlife really work. What Adi Shankaracharya is saying is that Shabara Swami actually took the argument he's presenting from Vyasa's Brahma Sutras, specifically from the Sutras I gave above.
So my question is, are there any other arguments that Shabara Swami took from the Brahma Sutras?
Do any Purva Mimamsa works or Vedanta works shed light on this? And for that matter, does anyone else agree with Adi Shankaracharya that Shabara Swami took his existence of soul argument from the Brahma Sutras? I discuss in this question how Ramanujacharya and other commentators don't even think the Sutras are talking about the existence of the soul.