Multiple valid viewpoints, contradictions and complexity
The first of the three pillars of transdisciplinarity is that reality is multi-dimensional. That means that there are multiple valid perspectives of the same reality. It is quite possible (and common) for two people to look at the same thing and interpret it differently and have different views about it.
This is closely related to the unity of knowledge, but goes a step further than purely putting different types of knowledge (e.g. academic and anecdotal knowledge) on the same level. It also includes the fact that we look at the same thing and see and interpret it differently purely because we look from different perspectives.
This is nothing new. Approaches like systems thinking, cybernetics and complexity theory already incorporate the fact that there are multiple layers of reality and that the position from which we observe reality impact significantly on how we see or interpret it. But the fact that transdisciplinarity incorporates this as a pillar makes it very suitable to engage with complex environments and messy real world situations.
The second pillar of transdisciplinarity, namely that it formally accepts contradictory views as valid parts of reality, further unpacks this. The logic of transdisciplinarity does not conclude if two contradictory views exist one is correct and the other incorrect. They are each evaluated on their own merit and both could end up being accepted.
The third pillar, namely that reality is complex, then concludes that a transdisciplinary approach of engaging reality always looks at reality as a complex phenomenon. This challenges the common preference of simplicity, or practice of simplifying to describe reality which is prevalent in many theoretical approaches and conceptual models or frameworks. It requires keeping the whole of the relevant reality in mind throughout the investigation.
What does this mean?
The three pillars of transdisciplinarity work together as a multi-dimensional description of what reality is like, making it possible to engage with such a reality in a rigorous way.
It is very suitable for engaging with complex, messy situations as they are in the world without trying to simplify them. It provides a rigorous approach where stakeholders from multiple different perspectives and viewpoints can participate in moving from the systems knowledge to the target knowledge to generate common good outcomes instead of outcomes optimised for certain aspects of reality. It is also very suitable to develop context-specific innovations that are fit for purpose, because of its ability to incorporate multiple dimensions and different types of knowledge simultaneously as the work progresses.