The two-truths doctrine is the belief that truth exists in conventional and ultimate forms, and that both forms are co-existant.

The doctrine is an especially important element of Buddhism and was first expressed in complete modern form by Nagarjuna, who based it on the Kaccāyanagotta Sutta.

In Buddhism, it is applied particularly to the doctrine of emptiness, in which objects are ultimately empty of essence, yet conventionally appear the contrary at any given moment in time, such that they neither exist nor do not exist.

In the Kaccāyanagotta Sutta, the Buddha, speaking

By and large, Kaccayana, this world is supported by a polarity, that of existence and non-existence. But when one sees the origination of the world as it actually is with right discernment, 'non-existence' with reference to the world does not occur to one. When one sees the cessation of the world as it actually is with right discernment, 'existence' with reference to the world does not occur to one.

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