This paper suggests defining three criteria to differentiate design and non-design, using the concept of effect in a phenomenological perspective. The central concept of this article is the concept of “effect of design,” defined as a three-dimensional result that occurs through usage and turns it into an “experience-to-live.” The three dimensions of the effect of design are the “ontophanic effect,” the “callimorphic effect” and the “socioplastic effect.” This approach is presented in the form of a philosophical manifesto in the geometrical style inspired by Spinoza’s Ethics. This article includes 1 general overview of the issue, 5 definitions, 3 axioms, 3 hypotheses and 3 developments.