Aesthetics in product design is commonly related to secondary functionality, i.e. expressing a specific lifestyle. We propose a broader scope for aesthetics in interactive product design, one that ties into a design's ethical dimension. Products change people's behaviours and experiences in interaction. Design is not only about incorporating primary or secondary functionality, but also includes ethical considerations about what kind of behaviours and experiences a product should invite. This paper describes an exploration of how to incorporate this ethical dimension through aesthetics. Central is the concept of to kalon as used by Aristotle, expressing the unity of the good (ethics) and the beautiful (aesthetics). In the workshop 'Ethics and aesthetics in interaction', designers create products with predefined primary functionality based on specific ethical systems, using aesthetics from related artworks. The results indicate that to kalon is a powerful means to innovate and to incorporate ethics in interactive product design.