The concept of levels of Reality, formulated in 1982, is the key concept of transdisciplinarity1.
One designates “Reality” as that which resists our experiences, representations, descriptions, images, or even mathematical formulations, and “level of Reality” means a set of systems which are invariant under certain general laws. Two levels of Reality are different if, while passing from one to the other, there is a break in the applicable laws and a break in fundamental concepts (like, for example, causality). Therefore, there is a discontinuity in the structure of levels of Reality.
The introduction of the levels of Reality induces a multidimensional and multi-referential structure of Reality, signifying the coexistence between complex plurality and open unity. Every level is characterized by its incompleteness; the laws governing this level are just a part of the totality of laws governing all levels. And even the totality of laws does not exhaust the entire Reality; we have also to consider the interaction between Subject and Object. The zone between two different levels and beyond all levels is a zone of non-resistance to our experiences, representations, descriptions, images, and mathematical formulations. The Gödelian structure of levels of Reality implies the impossibility of a self-enclosed complete theory. Knowledge is forever open.
The unity of levels of Reality of the Object and its complementary zone of non-resistance defines the transdisciplinary Object. The unity of levels of Reality of the Subject and this complementary zone of non-resistance defines the transdisciplinary Subject. The zone of non-resistance plays the role of a third between the Subject and the Object, an interaction term which allows the unification of the transdisciplinary Subject and the transdisciplinary Object. This interaction term is called the Hidden Third.
The Hidden Third restores the continuity between levels of Reality. In fact, there is a true non-separability of the Object, the Subject and the Hidden Third.
The ternary partition (Subject, Object, Hidden Third) is, of course, radically different from the binary partition (Subject vs. Object) of classical realism. Knowledge is neither exterior nor interior; it is simultaneously exterior and interior. The studies of the universe and of the human being sustain one another.
Levels of Reality are different from levels of organization as these have been defined in systemic approaches. Levels of organization do not presuppose a discontinuity in fundamental laws and in fundamental concepts. The same is true for several other contexts in which expressions like "regions of reality" or "levels of reality" are used. In general, a rigorous classification of regions in levels can not be obtained in the absence of discontinuity.
We will also analyze similarities and differences between the transdisciplinary notion of levels of Reality and the notion of "levels of reality" introduced by Werner Heisenberg in his work Philosophy - The manuscript of 1942, published in 1984.
The transdisciplinary notion of levels of Reality is incompatible with reduction of the spiritual level to the psychical level, of the psychical level to the biological level, and of the biological level to the physical level. Still these four levels are united through the Hidden Third, which however can not be captured in a theory.
The transdisciplinary notion of levels of Reality leads to a new vision of Personhood, based upon the inclusion of the Hidden Third.