Mike Rundle has posted a great article on the value of knowing your medium. The article is focused on user experience design for the web, but it applies to all mediums.

In addition to the examples that Mike provides in his article, I’d like to add that a designer who creates printed material knows the constraints of their medium. Print designers need to take into account the size of their canvas – is it a billboard or business card? They need to know technical limitations of the printer – is the process digital or press? Are my images at a sufficient resolution? The list goes on. You can’t effectively design for any medium without an understanding of how it works.

Mike’s article is in response to an article by Lukas Mathis which argues that designers who code (or at least know how to code) can negatively impact the design process. It’s worth a read, though I personally disagree with his theory.

I’d argue that because Lukas is both designer and coder he’s able to identify the issues that arise from being multi disciplinary. He’s not, however, taking into account the issues that arise from knowing too little about your target medium, which presents a host of other issues.