Material Design is design science (Daniel Hollick)

Why Material Design is our best attempt (yet) for a unifying theory of design. In 2013 Apple launched iOS 7 and the world fell in love with flat design. Apple by no means invented flat design (in fact Microsoft championed flat long before Apple), but they brought it to the massses. And they did it well. As a designer I set down a very familiar path. (medium.com)