tend to use solution conjectures as the means of developing their understanding of the problem". Abductive reasoning In the creation of new design proposals, designers have to infer possible solutions from the available problem information, their experience, and the use of non-deductive modes of thinking such as the use of analogies. This has been interpreted as a form of Peirce's abductive reasoning, called innovative abduction. Co-evolution of problem and solution In the process of designing, the designer's attention typically oscillates between their understanding of the problematic context and their ideas for a solution in a process of co-evolution of problem and solution. New solution ideas can lead to a deeper or alternative understanding of the problematic context, which in turn triggers more solution ideas. Representations and modelling Conventionally, designers communicate mostly in visual or object languages to translate abstract requirements into concrete objects. These 'languages' include traditional sketches and drawings but also extend to computer models and physical prototypes. The use of representations and models is closely associated with features of design thinking such as the generation and exploration of tentative solution concepts, the identification of what needs to be known about the developing concept, and the recognition of emergent features and properties within the representations. As a process for innovation A five-phase description of the design innovation process is offered by Plattner, Meinel, and Leifer as: (re)defining the problem, needfinding and benchmarking, ideating, building, and testing. Plattner, Meinel, and Leifer state: "While the stages are simple enough, the adaptive expertise required to choose the right inflection points and appropriate next stage is a high order intellectual activity that requires practice and is learnable." The process may also be thought of as a system of overlapping spaces rather than a sequence of orderly steps: inspiration, ideation, and implementation. Projects may loop back through inspiration, ideation, and implementation more than once as the team refines its ideas and explores new directions. Inspiration Generally, the design innovation process starts with the inspiration phase: observing how things and people work in the real world and noticing problems or opportunities. These problem formulations can be documented in a brief which includes constraints that gives the project team a framework from which to begin, benchmarks by which they can measure progress, and a set of objectives to be realized, such as price point, available technology, and market segment. Empathy In their book Creative Confidence, Tom