The very process of thinking, according to [George Herbert] Mead, is inconceivable without the power of language to evoke in the individual the meaning of his own gestures....In 'taking the role of the other,' as Mead puts it, the speaker observes his own behaviour from the point of view of the other person. The responses aroused in himself are those he anticipates will be aroused by the other person by his own gestures. The individual becomes an object to himself as it were. His own gestures become the subject of conscious awareness and critical examination for the efficacy of their meaning.
'Thinking,' or the emergence of mind, therefore involves more than consciousness, it involves self-consciousness. Our thinking takes the form of an internal conversation of gestures the completion of which implies the expression of that which one thinks to an audience. The significance of what one is going to say to others is anticipated before anything is actually said. No sound is made, but the effect is understood as though the speaker heard his utterances.
The individual, whether he eventually vocalises his thoughts or not, uses those responses which his own gestures to others call out in himself to determine what further thing he is going to say or do. This, for Mead, is the essence of rationality. The individual, through taking the attitudes of others towards himself, is able to bring his own social experience into consciousness and thereby achieves a level of effective control over that experience not possible within the limitations imposed by any conversation of (non-significant) gestures.
In Mead's terms therefore, rationality is inseparable from a process of social communication. By implication, rational design, if we accept Mead's definition of rationality, entails the selection of architectural forms on the basis of common meaning. The meaning that a built form arouses in the designer is the same as that which it arouses in those other persons involved in the social act of building. Meanings may of course be attached of which the designer is not aware....Without a basis of common meaning however, there can be no control on the part of the designer of the efficacy of his designs. Only when the designer anticipates such meaning, through the common response aroused in himself as well as in those others involved in the building process, does such control become possible.
Here then, we have the essential criteria for rational design. The designer, through taking the attitudes of others involved in the act of building, adjusts his own behaviour as a designer in the light of a critical awareness of the meaning his designs have for other persons. He becomes a self-conscious designer. The products of self-conscious, or rational design are significant symbols in built form.