Abstract. The article is dedicated to the composer’s and scientific heritage of the outstanding Ukrainian musicologist I.B. Pyaskovsky. The panorama of ideas, both realized and perspective for further research, is marked by the multi-vector direction. The composer’s creativity and scientific activity of I.B. Pyaskovsky are analyzed as a conjunctive dialogical algebra-logical model of the systemic nature of musical (compositional) and scientific thinking for the first time. It is exactly the study of the composer’s creativity of the scientist-musicologist as a logical and constructive embodiment of scientific research that is the purpose of this article.The beginning of scientific interests was the study of the logics of composition, musical thinking, analysis of Ukrainian folklore. In the mid-1990s, the field of scientific research was focused on the study of ancient and modern polyphony. Scientific studies of the 2000s are connected with computer modeling of the process of musical creativity and artificial intelligence. In fact, I.B. Pyaskovsky himself introduced the probabilistic and statistical methods and methods of modeling the creative process in Ukrainian musicology, which he used in the training courses of computer analysis of musical texts, harmony, polyphony, into the scientific use of Ukrainian musical science. The priority directions of scientific research are logical and constructive principles of musical thinking, logical and artistic in musical thinking, the phenomenon and evolution of musical thinking. The composer’s creativity in the article is represented by two polyphonic cycles – “udes and Fugues”and “ugues and Postludes” The first includes six preludes and fugues, the second includes six fugues and postludes. The composer’s concept of I. B. Pyaskovsky represents the author’s idea, presenting the opportunity to perform as one and both cycles (six preludes and fugues and six fugues and postludes), as well as individual works. All twelve keys are used by the tonal row of two cycles in the ascending chromatic sequence, these are major keys, of course in the modern sense. This is a reflection of the systematic nature of musical thinking of I. B. Pyaskovsky as a composer. The creative handwriting of the composer and musicologist I. B. Pyaskovsky, marked by a constructive expressionistic manner, opens up unlimited space for a variety of performance interpretations, different principles of using of the pedal to create coloristic effects, etc., thereby opening brilliant prospects for interpretation in the process of concert performance. The analyzed cycles are an illustration of the modern polyphonic technique, systemic nature, logical and constructive principles of musical thinking of the composer and musicologist I. B. Pyaskovsky.