||Design lives within two fundamental stages, the creative and the evolutionary. The first is that of producing the idea: this approach is built activating a logical jump between the existing and possible worlds that represent our wishes and thoughts. A design idea is the identification of a set of possibilities that goes beyond specific "solutions" but identifies the sense or the attainable quality. The field involved in this design stage is "how" the world may be transformed, not what the possible scenario may be. The second is the evolutionary stage, that of the development of the idea. This approach runs inside paths of refinement and increases in complexity of the projects. It involves the management of the project to reach the desired quality.Generative design is founded on the possibility to clearly separate the creative and the evolutionary stages of the idea. And the first is reserved for man (because creative processes, being activated from subjective interpretations and being abduptive paths and not deductive, inductive or analytical ones, can not be emulated by machines) and the second may be carried out using artificial devices able to emulate logical procedures. The emulation of evolutionary logics is useful for a very simple reason: for getting the best operative design control on complexity. Designers know very well that the quality of a project depends, very importantly, on the time spent designing. If the time is limited, the project can not evolve enough to attain the desired quality. If the available time is increased, the project acquires a higher quality due to the possibility of crossing various parallel evolutionary paths, to develop these and to verify their relative potential running through the cycle idea/evolution more times and in progress. (scheme1) This is not all. In a time-limited design activity, the architect is pressed into facing the formalization of performance requirements in terms of answering directly specific questions. He is pressed into analytically systematizing the requirements before him to quickly work on the evolution of the project. The design solution can be effective but absolutely not flexible. If the real need of the user is, even slightly, different to the hypothesized requirement, the quality of the project, as its ability to respond to needs, breaks down. Projects approached in this way, which we could call "analytical", are quickly obsolete, being tied up to the flow of fashion. A more "creative" approach, where we don't try to accelerate (therby simplifying) the design development path "deducting" from the requirements the formalization choices but we develop our idea using the requirements and the constraints as opportunities of increasing the complexity of the idea, enriching the design development path to reach a higher quality, needs, without doubt, more time. As well as being, of course, a creative and non-analytical approach. This design approach, which is "the" design path, is a voyage of discovery that is comparable to that of scientific research. The fundamental structure is the idea as a "not deducted" hypothesis concerning a quality and recognizability of attainable artwork, according to the architect's "subjective" point of view. The needs and the constraints, identified as fields of possible development of the project, are opportunities for the idea to develop and acquire a specific identity and complexity. Once possible scenarios of a project are formed, the same requirements and constraints will take part, as "verification of congruity", of the increase in quality. Then the cycle, once more, will be run again to reach more satisfactory results. It is, without doubt, an approach that requires time.