In his book, What the Buddha Taught, Walpola Rahula has a chapter on the Third Noble Truth — Nirodha. There, he discussed the notion of Absolute Truth in Buddhism:
Now, what is Absolute Truth? According to Buddhism, the Absolute Truth is that there is nothing absolute in the world, that everything is relative, conditioned and impermanent, and that there is no unchanging, everlasting, absolute substance like Self, Soul, or Ātman within or without. This is the Absolute Truth.
This is a relativist position, one that many conservatives detest. The problem with this position is that it could be self-contradicting. Rahula made this statement: “The Absolute Truth is that there is nothing absolute in the world.” But if this is an absolute statement, then the statement refutes itself — since it is a statement of absolute truth. It would be the same as saying, “The Absolute Truth is that there is no Absolute Truth.” Many Christian thinkers, especially Christian apologists, love to use this charge of self-contradiction to refute the Buddhist position and the moral relativist position. By refuting the no-Absolute-Truth position, they conclude that there must be Absolute Truth. But that is a non sequitur. For it presumes a false dichotomy — that there is either Absolute Truth or there is not. No everything in life is binary. Take the statement that “Francis is a boy.” If we establish that Francis is not a boy, then is it necessarily true that Francis is a girl? Today, we know that gender is not binary. In fact, many people identify their gender as “non-binary.” What if the Absolute cannot be classified as either existent or non-existent? A binary classification is not appropriate in many situations. For example, is a table male or female? Clearly, the male versus female classification is inappropriate for a table. It is a big assumption to take for granted that Absolute Truth has to be either existent or non-existent. Even the meaning of existence is not clear.
So, what is the Buddhist position? What would we consider as Truth in Buddhism? We know the Three Marks of Existence:
1. All conditioned things are impermanent.
2. All conditioned things are unsatisfactory.
3. All dharmas (both conditioned things and unconditioned things) are without self.
The Three Marks of Existence can be interpreted as a version of the no-Absolute-Truth position. Instead of saying that there is no Absolute Truth, the Buddhist position can be restated in a milder manner, more consistent with the scientific spirit, to avoid apparent contradiction. We can say that no absolutely true statement ( i.e. a statement that is not relative, conditioned, and mutable) has ever been discovered. There is no reason why we cannot make this statement if it is an empirical fact. Through the ages, no one has come up with a statement that is not relative, conditioned, situational, and subject to change. The no-Absolute-Truth position should not be stated with absolute certainty or finality. Rather, it should be stated as a report of empirical experience. It is essentially an agnostic position.
Can the Three Marks of Existence be falsified? According to Karl Popper, an unfalsifiable statement cannot be a scientific statement. The answer is “Yes.” If someone can find an example of something which is permanent, then it would falsify the statement that “All conditioned things are impermanent.” Similarly, if someone can find an example of something which can exist on its own and not dependent on other things, then the statement that “All dharmas are without self” would be falsified. All we need is one counterexample. But so far, no one has produced one.
To sum up, the statement that “There is no absolute truth” may be self-refuting or it may not be. It all depends on how it is interpreted. Certainly, the statement should not be asserted absolutely, for it would make it another absolute statement. The key is to assert it as a provisional statement, and as a statement of empirical experience. We can say, “So far, we have found nothing absolute; everything we have seen has been relative and conditional.” This would be enough to represent the Buddhist position, which is a relativist one. It is also a truthful one.