The Unicist Epistemology is based on the development of logical foundations and empirical justifications to sustain human knowledge. This epistemology is a pragmatic, structural and functionalist approach to knowledge. The pragmatism deals with the goal of this epistemology, which is to provide reliable knowledge in order to generate added value. At the same time, structuralism is required to integrate the knowledge of an entity and its restricted and wide contexts. Finally, functionalism makes results be a core aspect of the validity of knowledge. Knowledge is such when its use allows individuals to better adapt to an environment. But to be used, such knowledge needs to be stored in the individual’s long-term memory. The credibility of knowledge depends on having found the fundamentals that integrate the concept that defines the nature of an entity and having the necessary empirical justifications that make the acceptance of knowledge tangible. The Unicist Epistemology was developed to build reliable knowledge to deal with complex adaptive environments. This paper is a synthesis of the Unicist Epistemology that has been used for more than 15 years, since the ontology of destructive and non-destructive tests was developed, to build the knowledge objects of the applications of the Unicist Theory. The validation of concepts and fundamentals requires that individuals develop destructive and non-destructive tests, while the confirmation of operational knowledge only requires using non-destructive tests. The Unicist Epistemology provides, on the one hand, the basics of foundations, which deal with fundamental analysis, and on the other hand, the basics of cause-effect knowledge, which sustain the empirical justifications of knowledge. Language, as a tool of the conscious reasoning structure of humans, is a necessary condition to build conscious knowledge. Different types of languages allow building different types of knowledge. The paper includes the structure of the destructive and non-destructive tests that are used to confirm the validity of knowledge.