The origin of the Buddha's philosophy is a heavily debated topic in Indian philosophy. In the section on his teachings we've stated that the Buddha's teaching is derived from the Upanishads and this opinion is shared by a thinker as orthodox as the great Mimaamsaka Kumaarilla Bhatta himself. But this claim has been subjected to criticism by scholars, since it is perceived that while the central doctrine of the Upanishadic schools is the Atman or the Self, Buddhism has always stood in opposition to Atman theory with its doctrine of nairaatmaya (non-Self). So it is asserted that the Buddha's doctrine is not only original but also the exact opposite of the teaching of the Upanishads!

So we shall discuss here the relevant details and see for ourselves the veracity of the rival claims.

First let's look at the similarities. The goal of both the Upanishads and the Buddha is escape from the cycle of birth and death - samsaara - from this world of suffering. Both believe that it is desire that is at the origin of suffering and state that we should overcome desire to put an end to suffering. Both are against Vedic sacrifices as a means to salvation. And both stress ethical improvement and knowledge as the true means. For ethical improvement both are in agreement that control, charity and compassion should be practiced. But it is with respect to knowledge that there seems to be a difference between the two.

The Upanishads teach of an unchangable reality - which it says is supersensible - beyond the mind, the intellect and the senses. It terms this reality as brahman. Then it also defines the Self of man (Atman) as unchangable and supersensible. And in some Upanishads (Brhadaaranyaka, Chaandogya) the Atman is equated with brahman. Hence the Self is the Reality and salvation is attained when the non-dual (advaita) identity of the Atman and the brahman are realized by intuition.

But is this Self our "I" sense - the Ego?

The Upanishads assert that the Ego is the false "I" which feeds on the sensual pleasures of the world, while the true "I", the Self, is the changeless reality (Mundaaka Upanishad). It's due to the false identification of the Self with the false "I" that there's suffering. To know the Self, we must let go of all individuality - literally erase the Ego - and when we gradually, through self control and virtue transcend our false identification of ourselves with the senses-body-mind-Ego, that which is left - the residue - is the Self which is characterized as knowledge, existence and bliss - satchitaananda.

The Buddha was silent on the subject of nirvaana. He does not advocate prayer or worship, but ethical development and meditation which would lead to knowledge - nirvaana - which is escape from the cycle of birth and death. It's obvious that he believed that Reality was inherent in man.

But again, this is where he differs from the Upanishads. Though he didn't deny the Atman, neither did he endorse it. In some of his teachings he even comes across as hostile to the concept of the Self.

So did the Buddha not believe in the Upanishadic Self?

In the Majjhima Nikhaaya the brahmin samnyaasin of the Vatsa gotra (Vacchagotha) asks the Buddha whether the saint after deliverance is reborn, or not reborn, or both reborn and not reborn, or neither reborn nor not reborn?

The Buddha replies that, like the fire when running out of fuel becomes extinct, all form, feeling, perception, predispositions and consciousness (the five skandhas) by which one can predicate the existance of the saint, all that has been abandoned, uprooted, pulled out of ground like the palmyra tree and become non existant and not liable to spring up again in the future. The saint who's been released from what's styled form, feeling, perception, predispositions and consciousness, is deep, immeasurable, unfathomable like the mighty ocean. To say he is reborn, or not reborn, or both reborn and not reborn, or neither reborn nor not reborn, would not fit the case!

Simply put the Buddha was echoing the Upanishadic sentiment that reality was beyond intellectual comprehension.

Also though the Upanishads define the reality as Self - but being devoid of individuality it is actually not the Self. But that doesn't mean that the Self is totally different or an other to the "I" consciousness. For then ethical improvement and meditation would make no sense. So the Self is neither the "I", nor is it the not "I" - it is beyond logic and reason (The entire philosophical effort of the Vedic schools and the early Buddhist schools point to the futility of trying to reconcile with logic, a changeless Self underlying a changing Ego or empirical life without a Self). Though beyond logical comprehension, it is that due to which even the Ego exists. This is why the Buddha says to the brahmin Badari in the Kshudragama that the Self is infact not of the nature of the self. But so as not to confuse or discourage the aspirant the Upanishads define it as Self.

The Upanishads and the Buddha are pointing to the same thing, but from different standpoints - one from the positive viewpoint of the Self (Atman) and the other from the negative viewpoint of the non-Self (anaatman).

But why did they preach the doctrine in different ways?

We consider the following factors as the reasons that made the anatta doctrine a central feature of the Buddha's teaching in contrast to the Atman doctrine of the Upanishads :

1. For the Buddha all effort at philosophy - to know about reality is fundamentally a waste of time and it would only serve to distract the seeker from what was really essential - to be that reality - to attain nirvaana. That's the reason he clearly states that his is not a school of philosophy but a yaana or a vehicle to liberation. All use of the intellect is worthwhile only to structure the most effective path towards liberation and not to keep speculating about the nature of reality. Though there's an unchanging reality in man and it is the essence of his identity, still the greatest obstacle towards realizing this reality is the phenomenal self. To confuse the true self in man with his phenomenal self i.e, the ego, would totally counter productive in spiritual effort. So the teaching of anatta is not meant as a metaphysical doctrine, but as a psychological teaching - a blow to the phenomenal self whose existence is the greatest hindrance to liberation.
2. Another factor which might have given rise to the anatta doctrine is that the Buddha taught to all people. While a learned brahmin living a semi ascetic life might have little problem with ego or arrogance, for the normal man these manifestation of the phenomenal self pose the greatest hurdle towards liberation. Hence the utility of the anatta doctrine when the teaching is disseminated to the masses.
3. It should also be noted that traditionally the Vedic religion is world enveloping in philosophy. True, that renunciation is a part of the tradition - but that's only after the stages of student and householder have been successfully completed. It accepts artha (wealth) and kaama (desire) as two of the primary needs of life, but eventually subordinates them to dharma (virtue) and moksha (liberation). Though the Vedic doctrine preaches a Self to accommodate the first two stages of life, it eventually works towards erasing it in the last two stages of vaanaprastham (forest dweller) and samnyaasin (wandering mendicant). But the Buddha's fundamental goal is the cessation of suffering. Artha and kaama are evil as they cause suffering. Hence worldly life is rejected. One should vigilantly practice dharma to achieve moksha. Buddhism in contrast is essentially a monastic religion and since it didn't have to accomodate artha or kaama in its world view, the first step in its discipline is suppression of the Ego - hence the doctrine of anatta or non-Self.