Nagarjuna was an ancient Indian philosopher born in Southern India in the second century CE and is considered to be the most important Buddhist philosopher after Buddha. He embraced the belief that everything in the world is interconnected (known as the doctrine of “dependent origination”) and based on this principle concluded the impossibility for anything to have an independent existence or essence. Rather, for Nagarjuna, every “thing” is empty (sunyata), and it is our minds that differentiate “it” from everything else. Because everything is empty of independent existence, Nagarjuna shows the unreality of things such as causality, identity and motion. To do this, he differentiates between what is “conventionally” true and what is “ultimately” true.

Originally born as a Hindu in Southern India, Nagarjuna made his way North. There, Buddhists and Brahmanists (Hindu philosophers) would debate theoretical questions about the nature of being, God, and the soul. Here, Nagarjuna embraced became a part of what is known as Mahayana (“Greater Vehicle”) Buddhism. He believed that these theorists were creating fancy intellectual positions that were getting in the way of achieving enlightenment, and were deviating from the Buddha’s true teachings. In the Mulamadhyamakakarika (“Fundamental Wisdom of the Middle Way”), he uses their styles of argument in order to disprove their positions. In doing so, he became the founder of his own school of Buddhist philosophy known as the Madhyamika (Doctrine of the Middle Position).

The Buddha taught the doctrine of “dependent arising” (pratityasamutpada) which sees the world as fundamentally interconnected. He also taught that the world is in a constant state of flux, and that there is no true self. The “I” which we experience is in reality the result of the temporary unity of different physical and mental processes (anatta). Nagarjuna understands the world’s transient and impermanent nature to mean that nothing has its own essence or independent existence. Everything is “empty” (sunyata) in so far as it depends on other things in order to exist. For example, a table can only be said to exist in so far as four pieces of wood are connected to a base. If the legs are taken off, it is no longer a table. Therefore, it has no independent existence.

In demonstrating how everything in the world is “empty,” Nagarjuna differentiates between conventional and ultimate truth. It is a conventional truth that something exists, in so far as we are making a statement based on common sense, experience, and the relative meaning of language. For example, if I say that “I” exist, this is conventionally true. But ultimately, since there is no “I” but merely a temporary combination of physical and mental processes, this statement is untrue.

Using this distinction, Nagarjuna shows that causality is only conventionally true. For something to cause an effect, it would have to have it’s own independent existence. Since Nagarjuna denies that anything has it’s own independent existence, causality is only a conventional truth, and not an ultimately true. To say “this causes that” is to use language to communicate in a way that is not accurate with ultimate truth. Instead of causes, Nagarjuna explains that things are the result of conditions. For example, a candle is burning because it is lit. It’s not that lighting the candle caused it to burn, but rather that the candle’s burning is the result of the condition of it being lit. Likewise, the candle is burning because it is made out of wax. The “candle is burning” because of a number of different conditions which together allow us to understand it in this way.

Likewise, Nagarjuna explains that motion is only a conventional truth. He explains that motion can only exist if there is a mover, and for this reason, motion does not exist independently. Motion and the mover are dependent on each other. He says “If without a mover, it would not be correct to say that there is motion, then if there were no motion, how could there be a mover?” In this way, Nagarjuna uses logical reasoning, and in particular the method of reductio ad absurdum (“reducing to the absurd”) to support the Buddha‘s beliefs in the fundamental interconnectedness of reality and the impermanence and transience of the world, which he defines with his concept of “emptiness” (sunyata).

Nagarjuna’s principle of “emptiness” allowed him to defend Buddhist teachings against the new Buddhist and Brahmanic (Hindu) theories concerning the nature of reality. His epistemology (theory of knowledge), use of logic and analytic reasoning, understanding of the relative nature of language, and his critique of the metaphysics (understanding of reality) underlying common sense would greatly influence developments in Buddhist thought since.