Abstract
This paper aims to provide a basic explanation of existence, fundamental aspects of reality, and consciousness. Existence in its most general sense is identified with the principle of logical consistency: to exist means to be logically consistent. The essence of the principle of logical consistency is that every thing is what it is and is not what it is not. From this principle follows the existence of intrinsic, indescribable identities of things and relations between them. There are three fundamental, logically necessary relations: similarity, composition and instantiation. Set theory, mathematics, logic and science are presented as relational descriptions of reality. Qualities of consciousness (qualia) are identified with intrinsic identities of things or at least a certain subset of them, especially in the context of a dynamic form of organized complexity.