||In order to discuss this question it is necessary to reflect awhile on design methods in general. The usual categorization discusses 'generations' of design methods, but Levy (1981) proposes an alternative approach. He identifies five paradigm shifts during the course of the twentieth century which have influenced design methods debate. The first paradigm shift was achieved by 1920, when concern with industrial arts could be seen to have replaced concern with craftsmanship. The second shift, occurring in the early 1930s, resulted in the conception of a design profession. The third happened in the 1950s, when the design methods debate emerged; the fourth took place around 1970 and saw the establishment of 'design research'. Now, in the 1980s, we are going through the fifth paradigm shift, associated with the adoption of a holistic approach to design theory and with the emergence of the concept of design ideology. A major point in Levy's paper was the observation that most of these paradigm shifts were associated with radical social reforms or political upheavals. For instance, we may associate concern about public participation with the 1970s shift and the possible use (or misuse) of knowledge, information and power with the 1980s shift. What has emerged, however, from the work of colleagues engaged since the 1970s in attempting to underpin the practice of design with a coherent body of design theory is increasing evidence of the fundamental nature of a person's engagement with the design activity. This includes evidence of the existence of two distinctive modes of thought, one of which can be described as cognitive modelling and the other which can be described as rational thinking. Cognitive modelling is imagining, seeing in the mind's eye. Rational thinking is linguistic thinking, engaging in a form of internal debate. Cognitive modelling is externalized through action, and through the construction of external representations, especially drawings. Rational thinking is externalized through verbal language and, more formally, through mathematical and scientific notations. Cognitive modelling is analogic, presentational, holistic, integrative and based upon pattern recognition and pattern manipulation. Rational thinking is digital, sequential, analytical, explicatory and based upon categorization and logical inference. There is some relationship between the evidence for two distinctive modes of thought and the evidence of specialization in cerebral hemispheres (Cross, 1984). Design methods have tended to focus upon the rational aspects of design and have, therefore, neglected the cognitive aspects. By recognizing that there are peculiar 'designerly' ways of thinking combining both types of thought process used to perceive, construct and comprehend design representations mentally and then transform them into an external manifestation current work in design theory is promising at last to have some relevance to design practice.