This book contains 15 essays written between 1969 through 1983. The essays included are: (1) "Semantic Analysis of Verbs in Terms of Conceptual Situations"; (2) "'Because' and the Concepts of Causation"; (3) "The Development of Language as Purposive Behavior"; (4) "Adaptation and Viability"; (5) "On the Concept of Interpretation"; (6) "Piaget and the Radical Constructivist Epistemology"; (7) "The Construct of Identity or the Art of Disregarding a Difference"; (8) "The Concepts of Adaptation and Viability in a Radical Constructivist Theory of Knowledge"; (9) "Cybernetics, Experience, and the Concept of Self"; (10) "An Introduction to Radical Constructivism"; (11) "Feedback, Induction and Epistemology"; (12) "An Interpretation of Piaget's Constructivism"; (13) "An Attentional Model for the Conceptual Construction of Units and Numbers"; (14) "Subitizing-The Role of Figural Patterns in the Development of Numerical Concepts"; and (15) "Learning as Constructive Activity." These essays are categorized in three sections: language and semantics; constructivist epistemology; and concepts of number. A list of 106 publications written by the author from 1960 to 1987 is provided. (YP)