You can hear them laid out by the man himself in the trailer above for Rams, last year's documentary by Gary Hustwit, he of Helvetica (the documentary about the font) and Objectified (the documentary about industrial design that featured Rams as an interviewee).
Good design is innovative. "Design always comes about in connection with innovative technology. How can design be good if the technology is not on the same level?"
Good designmakes a product useful. "Good design optimizes usefulness and ignores anything that doesn't serve the purpose or works against it."
Good design is aesthetic. "Objects you use daily significantly shape your surroundings and your sense of well-being. Only something that is well-made can be beautiful."
Good designmakes a product understandable. "It makes it easy to understand the structure of the product. Even more, it can make the product 'talk.' Ideally, it explains itself best."
Good design is unobtrusive. "Products that serve a purpose have the characteristics of a tool. Their design should be neutral and leave room for the user's self-expression."
Good design is honest. "Honest means not trying to make a product look more innovative, powerful, or valuable than it really is."
Good design is long-lasting. "In contrast to fashionable design, it lasts many years even in our current throwaway society."
Good design is thorough down to the last detail. "Nothing should be arbitrary or left to chance. Thoroughness and precision are expressions of respect for the user."
Good design is environmentally friendly. "Design makes an important contribution to preserving the environment. It conserves resources and minimizes physical and visual pollution."
Good design is as little design as possible. "Back to simplicity. Back to purity. Less, but better.
The trailer illustrates each of these principles with one of Rams' designs, developed at Braun or elsewhere:
the T 1000 CD radio, the MPZ 21 citrus juicer, the 740 stool, the 620 chair.