Preface to the English edition.- Preface to the Polish edition.- I Introduction.- 1.1. Mathematical notation.- 1.2. Numerical systems.- 1.3. Elementary systems.- 1.4. States and histories.- 1.5. Complex systems.- 1.6. Empirical phenomena.- 1.7. Phase-space of a phenomenon and some related technical notions.- 1.8. Semi-interpreted languages.- 1.9. Fundamental semantic concepts.- 1.10. Formalized languages and the deductive concept of a theory.- 1.11. A criterion of consistency.- 1.12. The concept of a theory.- II Regularities.- 2.0. Two conventions.- 2.1. Two types of regularities.- 2.2. State-determined phenomena.- 2.3. Mathematical models for state transformations.- 2.4. History-determined phenomena.- 2.5. Definability.- 2.6. Ontological versus semantic definability.- 2.7. Surrounding conditions.- 2.8. Self-determined phenomena.- 2.9. Invariancy.- 2.10. Notes.- III Empirical Theories.- 3.1. Axiomatic versus set theoretical way of defining theories.- 3.2. Theories as deductive systems.- 3.3. The concept of truth.- 3.4. Empirical theories.- 3.5. Two examples of empirical theories.- 3.6. Models and theories of empirical phenomena.- IV Measurement.- 4.1. Semantic conception of measurement.- 4.2. Complete measurement structures.- 4.3. Approximate measurement.- 4.4. Theoretical versus operational conception of measurement.- 4.5. Notes.- V Operational Structures.- 5.0. Introductory assumptions.- 5.1. Verification procedures.- 5.2. Operational structures.- 5.3. A revised notion of regularity.- 5.4. The concept of truth as related to operational structures.- 5.5. Truth by convention.- 5.6. Confirmation procedures.- 5.7. Probabilistic models.- 5.8. Dispersive operational structures.- 5.9. Evolution of empirical theories.- VI Appendix.- 6.1. Complementary tests.- 6.2. Physical systems.- Index of Symbols.- Index of Names.