Ideation is an important activity of Design Thinking, a process that may benefit from different levels of automation in its activities. Preceded by Immersion and Analysis activities, Ideation can be enhanced by computational approaches like debate synthesis and mediation, sentiment analysis, and so on. In this paper an architecture for an extensible platform for ideation is addressed. Initially, it comprises a set of components to cope with those functionalities. The extensibility of this platform is in the sense that it shall allow the inclusion of new components like creation of domain ontologies for integration of different studies in the same domain. The general purpose of this platform is to support the creation of ideas by (i) constructing consensus among specialists and (ii) managing dissents in order to keep in track of marginal ideas that can become dominant ones as the discussion advances. It can be applied to many fields, like innovation, Studies of Future, definition of complex diagnoses, etc. Actually, this proposal came up from an experience with a study of future in which some experts had tried to envision trends for some years ahead in order to propose strategic actions for reaching a desired status for Brazil as a successful, fair, and inclusive country. The proposal includes an open and interactive computational environment to enable (i)  structuring debates in threads of discussion; (ii) the gathering of ideas about topics of interest; (iii) the debate on the ideas put forward in order to identify the most relevant ones; (iv) synthesis of a debate (anytime summarization); (v) identification of the prevailing sentiments in a debate; and (vi) identification of variables relevant for the sake of the debate target.