The philosophy of Vajrayana has emerged out of a fusion of mahayanic and Tantric elements. At first glance, the mahayanic concepts appear to be full of Mahayanic terms and concepts, obscure cults, tantric mandalas etc. which have been described in cryptic language. However, a closer inspection of the same reveals the building blocks of metaphysics beneath the surface of these texts. When pieced together, they form the basis of the philosophy of Vajrayana school of Buddhism. Though it does not have the sophistication and conceptual precision typical of Buddhism, nevertheless certain basic elements may be detected in the philosophy of Vajrayana.

Nature of Existence
The first step in the Vajrayanic investigation of reality is the comprehension of existence in its realistic and pluralistic appearance. The Abhidharmika delineation of dharmas into skandhas, ayatnas and dhatus is taken for granted here. The Madhyamika view that the Dharmas are sunya since they arise out of Dependant Origination is also accepted by the Vajrayana School. Though the Dharmas have no nature of their own, they appear in empirical experience. This, according to the Vajrayanists is because these dharmas are projected by the mind. It is essentially consciousness seen as an `other`. As long as the mind continues to act, the empirical reality is sustained; but ultimately the mind also ceases and consciousness alone exists as non-dual bliss. With the negation of the object, the subject function of consciousness also lapses and consciousness regains its intrinsic quiescence.

What is new about the Vajrayanic conception of Dharma is that they perceive a kind of homologous correspondence among them. They are not just seen as mere concepts, but as deities. These deities are seen as inhabiting the body of the principal deity as well as the internal mandala, the body of the sadhaka. In this way, each of the dharmas is visualised and experienced within the sadhaka during the meditative process of visualisation. The nishvabhavata of the dharmas is believed to be realized by the saddhaka during the process of visualisation.

Nature of Avidya
Empirical reality as it appears is actually the mental modification of consciousness. This is brought about by avidya. The two forms of avidya- jneyavarana and klesavarana- are believed to influence the mind and give expression to its creativity. Jneyavarana brings about a multiplicity of views (drstis) about the Real and thereby prevents from acquiring the knowledge about the real nature of Ultimate Reality. The other form of avidya, klesavarana, is responsible for the emotional responses to the empirical reality, which afflict the human mind.

Both Jneyavarana and klesavarana together create a sort of web of illusions about empirical reality. This is a complete process with views and categories and psychic responses. The removal of all these misconceptions and avarnas can be brought about by knowing the real nature of empirical existence in the Vajrayanic way. It is believed that once the nature of the world is known, the false views about it (Jneyavarana), and the accompanying inordinate mental afflictions (klesavarana), which prevent the saddhaka from attaining his goal will disappear.

Ultimate Reality as Vajra
The realisation of ultimate reality as the essence is Vajra, achieved through the removal of avidya. Though similar to the concept of sunyata of the Madhyamika and the vijnana of the yogacara, the concept of vajra is not synonymous with the two. Vajra, is the sunyata of dharmas {dharmasunyata), but not the sunyata of views (drsti-sunyata), as spoken of in Madhyamika. It is the absence of knower-knowledge duality (grahya-grahakabhava) as in Yogacara. The difference between the sunyata of the madhyamika and the vajra is that while the former is an epistemic entity, the latter is an ontological one. It is a firm essence (drdham saram). It agrees with Yogacara that the Ultimate Reality is non-dual consciousness but goes further to state that it is the Innate (sahaja) and is of the nature of Great Bliss (mahasukha). The idea of vajra encompasses a more extensive than that of sunyata, as vajra signifies a fusion of both sunyata and karuna and therefore signifies both.

Ultimate Reality as Bi-polar
Another philosophical foundation of Vajrayana is that it conceives of the Absolute as bi-polar. These two polarities are formed by sunyata and karuna, the two fundamental principles of Mahayana Buddhism. This polarity should not be mistaken as duality. The polarity referred to here is the inherent and inseparable condition of the absolute. The Vajrayanists hold that the empirical reality reflects this essential bi-polarity of the Absolute, in the form of the female and the male. It is believed that every individual in the psycho-physical realm is endowed with this polarity- one as female and the other as male.

Yoga: Union of Polarities
The goal of Vajrayana lies in the recognition and eventual union of the polarities within the body. The yogi is helped to identify himself as the male polarity and view the yoginis as the female polarity, and through their physical union, following the Vajrayanic prescription and the Guru`s instructions, attains psychic reintegration.

The yogi may perform this process of reintegration and union, purely as an internal process using the visualisation techniques prescribed by the Vajrayanic texts, under the guidance of a competent Guru. In the process of internal union, he visualises the two nadis, lalana and rasana, as the female and the male principles, and the central nadi, avadhuti, as the union of the two.

Nature of the Absolute as Bliss
Mahasukha or great bliss is provided by the state of re-integration. This great bliss is said to be beyond the realm of concepts. The Absolute is not something perceived as transcendent and sterile, as the sunyata of the Madhyamika, or only as the underlying non-dual consciousness of the yogacara. For the Vajrayanist too, the Absolute is inexpressible in terms of empirical categories, yet not altogether beyond human experience. In terms of expression the Absolute is sunya, but in terms of experience, it is Great Bliss. However, in this experience there is no subject-object duality.

These are therefore some of the basic tenets underlying the tenets of vajrayana. It is on the roots of these philosophical assumptions that the entire body of work of the vajrayana rests.