One of the things I "preach" in my class on Design Theory is that everyone who designs act based on some kind of design philosophy. It may be explicit or implicit, but it is there. A design philosophy influences how you think about design, its role, its purpose, how to do it, etc. I push my students to do four things.
First, to examine and reveal their own (existing) design philosophy, to make it as explicit as possible, in an honest way (usually they do not think they have one).
Secondly, to critically examine their own design philosophy, what it means, its consequences for practices, its strengths, and weaknesses, etc.
And then thirdly, to reflect on if their existing philosophy is what they want. What are they missing, what do they want to emphasize, and what do they see as their future strength as a designer.
And finally, to reflect on how they can change and develop their design philosophy in a desired direction.
I think this article about how Logitch has changed their design philosophy is a great example of the importance of knowing your design philosophy. This is how design philosophy becomes reality.