Logical Investigations. A Set of 3 Books (Volume 1, Volume 2, Part 1, Volume 2 Part 2)

"Logical Investigations" (1900–1901) by Edmund Husserl is the starting point of the phenomenological movement. The first volume of this work, "Prolegomena to Pure Logic," is devoted to a critique of the dominant directions in the theory of knowledge at the turn of the 19th and 20th centuries. Husserl identifies the main illness of philosophy in his time as psychologism—the contemporary projects aimed at the psychological foundation of logical-mathematical and philosophical knowledge. Using examples from the leading logical teachings of the second half of the 19th century, he proves that the psychological and, in general, empirical foundation of science overlooks the qualitative difference between empirical and ideal knowledge, ignores the special status of logical-mathematical laws, and leads to relativism in the theory of knowledge. At the end of the first volume, Husserl formulates the program of his own "Science of Science"—a new science aimed at investigating the aprioristic conditions for the possibility of scientific knowledge. Husserl's critique of psychologism initiated a broad discussion that involved most leading philosophers at the beginning of the 20th century.

In the introduction to the second volume of "Logical Investigations," the principle of the lack of presuppositions is clarified as the main principle of phenomenology, along with its correlational main requirement: "To the things themselves!", which becomes the slogan of the phenomenological movement. Phenomenology is introduced as a neutral science that should serve as the foundation for both logic and psychology. The first part of the second volume consists of five studies united by a common theme: the correlation of meanings as ideal unities and acts of consciousness that constitute meanings. The first study introduces the main distinctions: between a sign as an indication and a sign as an expression of meaning, between meanings in communicative speech and in solitary mental life, between the intention of meaning (empty intention) and the realization of meaning, between meaning and the object. The second study considers the difference between the intention of the general and the singular, with perception being posited as the necessary basis for discerning essence. The third and fourth studies examine the structural relations of meanings. The distinction introduced in the third study between independent and dependent parts prepares the main difference of the fourth study—between independent and dependent meanings. The idea of a purely logical grammar is put forward, which should establish a formal connection of meanings and allow the avoidance of absence of meaning and nonsense. In the fifth study, an outline of the phenomenological theory of consciousness as connections of experiences and as intentional acts is presented.

In the concluding, sixth study, which comprises the second part of the second volume of "Logical Investigations," the main aspects of phenomenological analysis of cognition are highlighted. The initial distinction of the first section is between objectifying (representation, judgment) and non-objectifying (question, desire, assumption) acts. The basic problem is whether all acts or only objectifying ones carry meanings; whether meanings are expressed only in judgment or also in questions, desires, etc.? The problem of cognition in the narrow sense of identifying the object is considered from the perspective of the compatibility and conflict of intentions in realization. In this context, a distinction is made between cognitive and intuitive intentions and levels of cognition. The final chapter of the first section examines the ideal of adequation in cognition and the relationship between truth and obviousness. Four concepts of truth are introduced, and a distinction is made between being in the sense of truth and being as a connection in judgment. Husserl's reflections on being, which trace back to the famous Kantian thesis, had a significant impact on the formulation of the question of being in Heidegger. In the second section, the consideration of objective categorial forms and ideal objectivity is revealed as the structure of categorial contemplation, founded in perception but not reducible to sensory perceptions or purely intellectual activity. In this process, the concepts of perception and contemplation receive the necessary expansion.