For most religions, the idea of a soul is a vital necessity. The soul here is by definition an independent entity which exists in our body independent of both our flesh and consciousness. It is the true master of both, and all religious teaching is geared towards this.
However, in Advaita there is no necessity of such an independent entity. This is because, in contrast to other religions, our existence here is considered a relative reality only, and nothing here has an independent existence. So there is no need to postulate a soul as an entity with a special power. In modern terms, the soul in Advaita is our individual consciousness only. This definition, of the soul as the individual consciousness itself, is to be found repeatedly in the Upanishads also.
The definition of the soul as an independent entity, however, is necessary in Advaita in one situation, to explain the special Hindu theory of what happens on death — Reincarnation. It is while explaining reincarnation that we find the upanishadic sutras dealing with the soul as an independent entity. For reincarnation to work, we of course need an independent entity, an entity which can exist independent of our consciousness and our body. This is necessary because only such an entity would be able to survive the death of our body and our consciousness and transcend them to take up another consciousness and body.
Because reincarnation is such an important part of the Hindu ethos, it is ultimately this definition of the soul which has stuck. Hindu teachings in general teach of an independent soul, called variously as ‘atman’ or ‘jiva’.
However, it is my contention that the overall import of the Upanishads is not such a definition and the definition of the soul as the individual consciousness itself can be very well substantiated by the Upanishads itself.
Perhaps also, the point, that defining the soul as an entity independent of the body–mind and also existing apart from the Brahman, led to a definition of three levels of existence, was not so clearly understood. Or perhaps, the ancient seers as also their commentators like Sankaracharya, did not feel the need to clearly differentiate between these two viewpoints, considering the difference to be unimportant. However, this is not so in the modern context, as defining a soul apart from consciousness contradicts our physiological, psychological and also other scientific knowledge like that of computers or evolution. Hence we need to clearly differentiate between these viewpoints.

Why is it necessary in a modern understanding of Advaita to define the soul as the individual consciousness, and conversely, to rule out the soul as an independent entity?

There are a number of reasons why it is difficult to accept the idea of an independent entity living in our bodies. I have already enumerated this in my book
The main objection is scientific. One of the most important functions of the soul in traditional religions was that it gave ‘life’ to us, it provided the animation to our mechanical bodies. But this is now not necessary, we know now how life has evolved and that life is self sustaining and does not need any input from outside. We also know now that our consciousness is also self sustaining, and this also does not need any input from outside. The functioning of our brain is also understood to a fair extent, enough so that we know that there is no entity which ‘does the function of seeing’, ‘hearing’, etc.
There are a number of logical problems also, like how the soul would connect to our body, whether trees and animals have soul, etc.
For all these reasons, which I have discussed in the book, it is far more scientific and logical to define the soul as consciousness itself.
We should now look at the second question,

Why is it necessary to have the soul as an independent entity?

In the context of Advaita, the answer is simple — reincarnation. Reincarnation is a part of the hindu ethos, and for reincarnation, a soul is vital. If we define the soul as consciousness alone, then reincarnation also will not work. Both are necessary for each other.
There are of course any number of problems with reincarnation theory also. This also I have enumerated in my book.
Reincarnation again is supported in a number of instances in the Upanishads. The same sections which support reincarnation also support the soul as an independent entity. But though the sections supporting reincarnation are by far the majority, there are also a number of instances where reincarnation is not stated as a necessity, and a careful reading of the sutras can show that reincarnation is not a vital part of the Upanishads.
Hence, if we do not accept reincarnation, we do not need anymore to have this idea of a separate soul. Or we can argue from the opposite side and say that once we do not believe in a separate soul, we cannot believe in reincarnation.
A modern Advaita can safely dispense with these two ideas while still sticking to the core of Advaita, and thus have a system of beliefs which can conform to the most vigorous logic and also to present science.
Two other ideas that I have discussed in my book in terms of a modern understanding of Advaita is a realistic ontology in place of an idealistic one, and a conjecture regarding what happens to us on death. This also I will discuss further in terms of the sutras.
For this interpretation, I have relied on the translations by Swami Vireswarananda, Swami Gambhirananda and Swami Madhavananda brought out by the Advaita ashrama. These are the authorative translations of the Upanishas by some of the most knowledgeable experts in Sanskrit texts .
I also intend to use sutras from the ten major Upanishads only, as I feel they provide enough material to support my interpretation. The Vedas are the Brihadaranyaka Upanishad, Chandogya Upanishad, Isa, Mundaka, Mandukya, Katha, Taittriya, Aittriya and Prasna Upanishads. My (well thumbed) copies of these translations are:

• Brihadaranyaka Upanishad (with commentary of Sankaracharya): translated by Swami Madhavananda; Published by Advaita Ashrama (eighth impression, April 1993).


• Chandogya Upanishad (with commentary of Sankaracharya): translated by Swami Gambhirananda; Published by Advaita Ashrama (second edition, November 1992)


• Mandukya Upanishad (with Karika of Gaudapada and commentary of Sankaracharya); Translated by Swami Gambhirananda; Puvlished by Advaita Ashrama (First Edition, July 1979)


• Eight Upanishads (with commentary of Sankaracharya) Vol I: translated by Swami Gambhirananda; Published by Advaita Ashrama (second revised edition, January 1989, Reprint November 1991)


• Eight Upanishads (with commentary of Sankaracharya) Vol II: translated by Swami Gambhirananda; Published by Advaita Ashrama ( Ninth Impression November 1992)

I will deal directly with the sutras themselves in putting forward my opinion. Along with this, I will include some comments on Sankaracharya’s commentary. However, I have not gone into details on his commentary mainly because I wanted to concentrate on the Upanishads, and Upanishads alone. For the same reason I have not dealt with the Brahma Sutras or with Gaudipada’s Karika on the Mandukya Upanishad.END=NAM MO SAKYAMUNI BUDDHA.( 3 TIMES ).WORLD VIETNAMESE BUDDHIST ORDER=VIETNAMESE BUDDHIST NUN=GOLDEN LOTUS MONASTERY=THE EIGHTFOLD PATH.THICH CHAN TANH.THE MIND OF ENLIGHTMENT.AUSTRALIA,SYDNEY.7/1/2015.