This book presents a systematic examination of the science of design, proposing a framework that places human choice and agency at the center of design activity. The author analyzes the cognitive processes underlying design practice and offers a structured account of how design thinking differs from, and complements, scientific analysis. The book provides a conceptual foundation relevant to researchers and practitioners engaged in complex problem solving.

Core topics such as design methodology, modes of thought, and the processes of synthesis and analysis are discussed in detail. Through careful consideration of the logical structure of design, the chapters contrast design-oriented reasoning with traditional scientific approaches and outline the contours of an emerging academic field. Particular attention is given to contemporary issues, including environmental sustainability and the ethical dimensions of technology, examined from the perspective of design responsibility.

Intended for scholars, engineers, and students with an interest in design theory, engineering, the humanities, and related disciplines, this book contributes to an understanding of how design processes can be analyzed and improved. It offers a measured and rigorous perspective on design thinking and its role in addressing societal and technological challenges.

Hiroyuki Yoshikawa is the president of the International Professional University in Technology. He received his Doctor of Engineering degree from the University of Tokyo in 1964. He was an associate professor, professor, and the president of the University of Tokyo in 1966–1978, 1978–1993, and 1993–1997, respectively. He also served as a guest professor at Churchill College of the University of Cambridge in 1997–1998; the president of  the University of the Air (currently the Open University of Japan) in 1998–2000; the president of the National Institute of Advanced Industrial Science and Technology (AIST) in 2000–2008; and the director general of the Center for Research and Development of the Japan Science and Technology Agency in 2008–2022. He has been the president of the International Professional University of Technology since 2022.

Professor Yoshikawa is known for putting forward general design theory that unifies established design methods in individual fields such as architectural design and mechanical design.