When considering design theory, I find that I characterize a good architectural design as one that is built with a "puzzle piece" mentality. This means that ideally the best architeture is one that focuses on several intricate pieces that fit together to form one unified whole. Hence, there becomes two essential criterions for design: First, design must be logical and clearly thought out, and there must be a precise execution of an idea. The space between what is thought to work and what is proven to do such must be minimal for credibility purposes, and to set a firm foundation on which a project is able to stand. Secondly, and perhaps most importantly; there must be fluidity. Design should not flow sequentially - that is to say that there should not be definite beginnings and endings in a design, but rather a unified whole in which there is compression, expansion, and movement not only spatially, but idealistically as well. Another important aspect of design to be considered is the language it speaks. While it is necessary to dialogue architectually; not only in the way that a project is read when being presented, but in the way it dialogues with its site and the contraints thereof; there still must be an innate simplicity evident. The non-architect must be able to coherently read what is being presented in order to even begin to appreciate it or imagine inhabiting the space. This becomes of chief important as well, as we design; not only for ourselves, but for the "common" individual - the client.
Although it seems as though this design theory is so well known that it could go without mention; it is far too important to exclude, and that is the idea of form follows funtion. Though possessing the ability to be progressive in nature; design must remain true. That idea of truth becomes living in the form follows function mentality. This is almost the common sense of design - a courtyard must breath and a living space must have things essential for living. Design should begin with the consideration of what the structure is to house, and end in evaluation of how effectively it does such. Thus this is both the alpha and omega of design; once again tying into the idea of design as a fluid process.