Since open computational systems are complex and dynamic structures with a great (but unknown) number of autonomous interacting entities, designers face up to a difficult problem: how can they completely specify such systems? We call Living Design the biologically inspired solution we expound here and which consists of the observation and manipulation during the design phase of the system being built as it "lives". More formally, in terms of design methodology, we propose an object-agent overlapping processes shifting which is an extension and modification of the classical design phases. This is to be realized in our work-in-progress adaptive multi-agent system methodology called ADELFE, which is centered on the AMAS theory also briefly expounded here.